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Chen X, Wang K, Mufti FUD, Xu D, Zhu C, Huang X, Zeng C, Jin Q, Huang X, Yan YH, Dong MQ, Feng X, Shi Y, Kennedy S, Guang S. Germ granule compartments coordinate specialized small RNA production. Nat Commun 2024; 15:5799. [PMID: 38987544 PMCID: PMC11236994 DOI: 10.1038/s41467-024-50027-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 06/26/2024] [Indexed: 07/12/2024] Open
Abstract
Germ granules are biomolecular condensates present in most animal germ cells. One function of germ granules is to help maintain germ cell totipotency by organizing mRNA regulatory machinery, including small RNA-based gene regulatory pathways. The C. elegans germ granule is compartmentalized into multiple subcompartments whose biological functions are largely unknown. Here, we identify an uncharted subcompartment of the C. elegans germ granule, which we term the E granule. The E granule is nonrandomly positioned within the germ granule. We identify five proteins that localize to the E granule, including the RNA-dependent RNA polymerase (RdRP) EGO-1, the Dicer-related helicase DRH-3, the Tudor domain-containing protein EKL-1, and two intrinsically disordered proteins, EGC-1 and ELLI-1. Localization of EGO-1 to the E granule enables synthesis of a specialized class of 22G RNAs, which derive exclusively from 5' regions of a subset of germline-expressed mRNAs. Defects in E granule assembly elicit disordered production of endogenous siRNAs, which disturbs fertility and the RNAi response. Our results define a distinct subcompartment of the C. elegans germ granule and suggest that one function of germ granule compartmentalization is to facilitate the localized production of specialized classes of small regulatory RNAs.
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Affiliation(s)
- Xiangyang Chen
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of USTC, The USTC RNA Institute, Ministry of Education Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Life Sciences, Division of Life Sciences and Medicine, Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Ke Wang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of USTC, The USTC RNA Institute, Ministry of Education Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Life Sciences, Division of Life Sciences and Medicine, Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Farees Ud Din Mufti
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of USTC, The USTC RNA Institute, Ministry of Education Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Life Sciences, Division of Life Sciences and Medicine, Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Demin Xu
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of USTC, The USTC RNA Institute, Ministry of Education Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Life Sciences, Division of Life Sciences and Medicine, Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Chengming Zhu
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of USTC, The USTC RNA Institute, Ministry of Education Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Life Sciences, Division of Life Sciences and Medicine, Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Xinya Huang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of USTC, The USTC RNA Institute, Ministry of Education Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Life Sciences, Division of Life Sciences and Medicine, Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Chenming Zeng
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of USTC, The USTC RNA Institute, Ministry of Education Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Life Sciences, Division of Life Sciences and Medicine, Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Qile Jin
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of USTC, The USTC RNA Institute, Ministry of Education Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Life Sciences, Division of Life Sciences and Medicine, Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Xiaona Huang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of USTC, The USTC RNA Institute, Ministry of Education Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Life Sciences, Division of Life Sciences and Medicine, Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Yong-Hong Yan
- National Institute of Biological Sciences, Beijing, 102206, China
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing, 102206, China
| | - Xuezhu Feng
- School of Basic Medicine, Anhui Medical University, Hefei, China.
| | - Yunyu Shi
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of USTC, The USTC RNA Institute, Ministry of Education Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Life Sciences, Division of Life Sciences and Medicine, Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, Anhui, 230027, China.
| | - Scott Kennedy
- Department of Genetics, Blavatnik Institute at Harvard Medical School, Boston, MA, 02115, USA.
| | - Shouhong Guang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of USTC, The USTC RNA Institute, Ministry of Education Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Life Sciences, Division of Life Sciences and Medicine, Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, Anhui, 230027, China.
- CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Hefei, Anhui, 230027, China.
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2
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Price IF, Wagner JA, Pastore B, Hertz HL, Tang W. C. elegans germ granules sculpt both germline and somatic RNAome. Nat Commun 2023; 14:5965. [PMID: 37749091 PMCID: PMC10520050 DOI: 10.1038/s41467-023-41556-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 09/08/2023] [Indexed: 09/27/2023] Open
Abstract
Germ granules are membrane-less organelles essential for small RNA biogenesis and germline development. Among the conserved properties of germ granules is their association with the nuclear membrane. Recent studies demonstrated that LOTUS domain proteins, EGGD-1 and EGGD-2 (also known as MIP-1 and MIP-2 respectively), promote the formation of perinuclear germ granules in C. elegans. This finding presents a unique opportunity to evaluate the significance of perinuclear localization of germ granules. Here we show that loss of eggd-1 causes the coalescence of germ granules and formation of abnormal cytoplasmic aggregates. Impairment of perinuclear granules affects certain germline classes of small RNAs including Piwi-interacting RNAs. Transcriptome profiling reveals overexpression of spermatogenic and cuticle-related genes in eggd-1 hermaphrodites. We further demonstrate that disruption of germ granules activates HLH-30-mediated transcriptional program in somatic tissues. Collectively, our findings underscore the essential role of EGGD-1 in germ granule organization and reveal an unexpected germ granule-to-soma communication.
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Affiliation(s)
- Ian F Price
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH, 43210, USA
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, 43210, USA
| | - Jillian A Wagner
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH, 43210, USA
| | - Benjamin Pastore
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH, 43210, USA
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, 43210, USA
| | - Hannah L Hertz
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH, 43210, USA
| | - Wen Tang
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA.
- Center for RNA Biology, The Ohio State University, Columbus, OH, 43210, USA.
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3
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Du Z, Shi K, Brown JS, He T, Wu WS, Zhang Y, Lee HC, Zhang D. Condensate cooperativity underlies transgenerational gene silencing. Cell Rep 2023; 42:112859. [PMID: 37505984 PMCID: PMC10540246 DOI: 10.1016/j.celrep.2023.112859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 05/26/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023] Open
Abstract
Biomolecular condensates have been shown to interact in vivo, yet it is unclear whether these interactions are functionally meaningful. Here, we demonstrate that cooperativity between two distinct condensates-germ granules and P bodies-is required for transgenerational gene silencing in C. elegans. We find that P bodies form a coating around perinuclear germ granules and that P body components CGH-1/DDX6 and CAR-1/LSM14 are required for germ granules to organize into sub-compartments and concentrate small RNA silencing factors. Functionally, while the P body mutant cgh-1 is competent to initially trigger gene silencing, it is unable to propagate the silencing to subsequent generations. Mechanistically, we trace this loss of transgenerational silencing to defects in amplifying secondary small RNAs and the stability of WAGO-4 Argonaute, both known carriers of gene silencing memories. Together, these data reveal that cooperation between condensates results in an emergent capability of germ cells to establish heritable memory.
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Affiliation(s)
- Zhenzhen Du
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430032, China
| | - Kun Shi
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430032, China
| | - Jordan S Brown
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Tao He
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430032, China
| | - Wei-Sheng Wu
- Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan
| | - Ying Zhang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430032, China.
| | - Heng-Chi Lee
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA.
| | - Donglei Zhang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430032, China; Cell Architecture Research Institute, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
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4
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Brown JS, Zhang D, Gaylord O, Chen W, Lee HC. Sensitized piRNA reporter identifies multiple RNA processing factors involved in piRNA-mediated gene silencing. Genetics 2023; 224:iyad095. [PMID: 37210214 PMCID: PMC10691750 DOI: 10.1093/genetics/iyad095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 02/10/2023] [Accepted: 05/03/2023] [Indexed: 05/22/2023] Open
Abstract
Metazoans guard their germlines against transposons and other foreign transcripts with PIWI-interacting RNAs (piRNAs). Due to the robust heritability of the silencing initiated by piRNAs in Caenorhabditis elegans (C. elegans), previous screens using C. elegans were strongly biased to uncover members of this pathway in the maintenance process but not in the initiation process. To identify novel piRNA pathway members, we have utilized a sensitized reporter strain which detects defects in initiation, amplification, or regulation of piRNA silencing. Using our reporter, we have identified Integrator complex subunits, nuclear pore components, protein import components, and pre-mRNA splicing factors as essential for piRNA-mediated gene silencing. We found the small nuclear processing cellular machine termed the Integrator complex is required for both type I and type II piRNA production. Notably, we identified a role for nuclear pore and nucleolar components NPP-1/Nup54, NPP-6/Nup160, NPP-7/Nup153, and FIB-1 in promoting the perinuclear localization of anti-silencing CSR-1 Argonaute, as well as a role for Importin factor IMA-3 in nuclear localization of silencing Argonaute HRDE-1. Together, we have shown that piRNA silencing in C. elegans is dependent on evolutionarily ancient RNA processing machinery that has been co-opted to function in the piRNA-mediated genome surveillance pathway.
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Affiliation(s)
- Jordan S Brown
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Donglei Zhang
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Olivia Gaylord
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Wenjun Chen
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
- Department of Laboratory Medicine, Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong Province 510000, China
| | - Heng-Chi Lee
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
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5
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Liu L, Wang X, Zhao W, Li Q, Li J, Chen H, Shan G. Systematic characterization of small RNAs associated with C. elegans Argonautes. SCIENCE CHINA. LIFE SCIENCES 2023:10.1007/s11427-022-2304-8. [PMID: 37154856 DOI: 10.1007/s11427-022-2304-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 12/28/2022] [Indexed: 05/10/2023]
Abstract
Argonaute proteins generally play regulatory roles by forming complexes with the corresponding small RNAs (sRNAs). An expanded Argonaute family with 20 potentially functional members has been identified in Caenorhabditis elegans. Canonical sRNAs in C. elegans are miRNAs, small interfering RNAs including 22G-RNAs and 26G-RNAs, and 21U-RNAs, which are C. elegans piRNAs. Previous studies have only covered some of these Argonautes for their sRNA partners, and thus, a systematic study is needed to reveal the comprehensive regulatory networks formed by C. elegans Argonautes and their associated sRNAs. We obtained in situ knockin (KI) strains of all C. elegans Argonautes with fusion tags by CRISPR/Cas9 technology. RNA immunoprecipitation against these endogenously expressed Argonautes and high-throughput sequencing acquired the sRNA profiles of individual Argonautes. The sRNA partners for each Argonaute were then analyzed. We found that there were 10 Argonautes enriched miRNAs, 17 Argonautes bound to 22G-RNAs, 8 Argonautes bound to 26G-RNAs, and 1 Argonaute PRG-1 bound to piRNAs. Uridylated 22G-RNAs were bound by four Argonautes HRDE-1, WAGO-4, CSR-1, and PPW-2. We found that all four Argonautes played a role in transgenerational epigenetic inheritance. Regulatory roles of the corresponding Argonaute-sRNA complex in managing levels of long transcripts and interspecies regulation were also demonstrated. In this study, we portrayed the sRNAs bound to each functional Argonaute in C. elegans. Bioinformatics analyses together with experimental investigations provided perceptions in the overall view of the regulatory network formed by C. elegans Argonautes and sRNAs. The sRNA profiles bound to individual Argonautes reported here will be valuable resources for further studies.
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Affiliation(s)
- Lei Liu
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Basic Medical Sciences, Division of Life Science and Medicine, University of Science and Technology of China, Hefei, 230027, China
| | - Xiaolin Wang
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Basic Medical Sciences, Division of Life Science and Medicine, University of Science and Technology of China, Hefei, 230027, China.
| | - Wenfang Zhao
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Basic Medical Sciences, Division of Life Science and Medicine, University of Science and Technology of China, Hefei, 230027, China
| | - Qiqi Li
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Basic Medical Sciences, Division of Life Science and Medicine, University of Science and Technology of China, Hefei, 230027, China
| | - Jingxin Li
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Basic Medical Sciences, Division of Life Science and Medicine, University of Science and Technology of China, Hefei, 230027, China
| | - He Chen
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Anhui University, Hefei, 230601, China
| | - Ge Shan
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Basic Medical Sciences, Division of Life Science and Medicine, University of Science and Technology of China, Hefei, 230027, China.
- Department of Pulmonary and Critical Care Medicine, Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.
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6
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Ma B, Wang S, Wu W, Shan P, Chen Y, Meng J, Xing L, Yun J, Hao L, Wang X, Li S, Guo Y. Mechanisms of circRNA/lncRNA-miRNA interactions and applications in disease and drug research. Biomed Pharmacother 2023; 162:114672. [PMID: 37060662 DOI: 10.1016/j.biopha.2023.114672] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 04/03/2023] [Accepted: 04/06/2023] [Indexed: 04/17/2023] Open
Abstract
In recent years, breakthroughs in bioinformatics have been made with the discovery of many functionally significant non-coding RNAs (ncRNAs). The discovery of these ncRNAs has further demonstrated the multi-level characteristics of intracellular gene expression regulation, which plays an important role in assisting diagnosis, guiding clinical drug use and determining prognosis in the treatment process of various diseases. microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) are the three major types of ncRNAs that interact with each other. Studies have shown that lncRNAs and circRNAs can sponge miRNAs, thereby influencing normal physiological processes and regulating mRNA expression and, thus, the physiological state of cells. This paper summarizes the mechanism of action and research progress of the three ncRNA and seven types of modalities. This summary is intended to provide new ideas for diagnosing and treating diseases and researching and developing new drugs.
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Affiliation(s)
- Benchi Ma
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China
| | - Shihao Wang
- College of Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China
| | - Wenzheng Wu
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China
| | - Pufan Shan
- College of Acupuncture and Massage, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China
| | - Yufan Chen
- College of Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China
| | - Jiaqi Meng
- College of Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China
| | - Liping Xing
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China
| | - Jingyi Yun
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China
| | - Longhui Hao
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China
| | - Xiaoyu Wang
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China.
| | - Shuyan Li
- College of Foreign Languages, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China.
| | - Yinghui Guo
- College of Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China; Laboratory of Liver Viscera-State & Syndrome of Emotional Disease, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China.
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7
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Liu S, Sharma U. Sperm RNA Payload: Implications for Intergenerational Epigenetic Inheritance. Int J Mol Sci 2023; 24:5889. [PMID: 36982962 PMCID: PMC10052761 DOI: 10.3390/ijms24065889] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 03/03/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023] Open
Abstract
There is mounting evidence that ancestral life experiences and environment can influence phenotypes in descendants. The parental environment regulates offspring phenotypes potentially via modulating epigenetic marks in the gametes. Here, we review examples of across-generational inheritance of paternal environmental effects and the current understanding of the role of small RNAs in such inheritance. We discuss recent advances in revealing the small RNA payload of sperm and how environmental conditions modulate sperm small RNAs. Further, we discuss the potential mechanism of inheritance of paternal environmental effects by focusing on sperm small RNA-mediated regulation of early embryonic gene expression and its role in influencing offspring phenotypes.
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Affiliation(s)
| | - Upasna Sharma
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA 95064, USA
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8
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Piombo E, Kelbessa BG, Sundararajan P, Whisson SC, Vetukuri RR, Dubey M. RNA silencing proteins and small RNAs in oomycete plant pathogens and biocontrol agents. Front Microbiol 2023; 14:1076522. [PMID: 37032886 PMCID: PMC10080066 DOI: 10.3389/fmicb.2023.1076522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 03/03/2023] [Indexed: 04/11/2023] Open
Abstract
Introduction Oomycetes cause several damaging diseases of plants and animals, and some species also act as biocontrol agents on insects, fungi, and other oomycetes. RNA silencing is increasingly being shown to play a role in the pathogenicity of Phytophthora species, either through trans-boundary movement of small RNAs (sRNAs) or through expression regulation of infection promoting effectors. Methods To gain a wider understanding of RNA silencing in oomycete species with more diverse hosts, we mined genome assemblies for Dicer-like (DCL), Argonaute (AGO), and RNA dependent RNA polymerase (RDRP) proteins from Phytophthora plurivora, Ph. cactorum, Ph. colocasiae, Pythium oligandrum, Py. periplocum, and Lagenidium giganteum. Moreover, we sequenced small RNAs from the mycelium stage in each of these species. Results and discussion Each of the species possessed a single DCL protein, but they differed in the number and sequence of AGOs and RDRPs. SRNAs of 21nt, 25nt, and 26nt were prevalent in all oomycetes analyzed, but the relative abundance and 5' base preference of these classes differed markedly between genera. Most sRNAs mapped to transposons and other repeats, signifying that the major role for RNA silencing in oomycetes is to limit the expansion of these elements. We also found that sRNAs may act to regulate the expression of duplicated genes. Other sRNAs mapped to several gene families, and this number was higher in Pythium spp., suggesting a role of RNA silencing in regulating gene expression. Genes for most effector classes were the source of sRNAs of variable size, but some gene families showed a preference for specific classes of sRNAs, such as 25/26 nt sRNAs targeting RxLR effector genes in Phytophthora species. Novel miRNA-like RNAs (milRNAs) were discovered in all species, and two were predicted to target transcripts for RxLR effectors in Ph. plurivora and Ph. cactorum, indicating a putative role in regulating infection. Moreover, milRNAs from the biocontrol Pythium species had matches in the predicted transcriptome of Phytophthora infestans and Botrytis cinerea, and L. giganteum milRNAs matched candidate genes in the mosquito Aedes aegypti. This suggests that trans-boundary RNA silencing may have a role in the biocontrol action of these oomycetes.
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Affiliation(s)
- Edoardo Piombo
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Bekele Gelena Kelbessa
- Department of Plant Breeding, Horticum, Swedish University of Agricultural Sciences, Lomma, Sweden
| | - Poorva Sundararajan
- Department of Plant Breeding, Horticum, Swedish University of Agricultural Sciences, Lomma, Sweden
| | - Stephen C. Whisson
- Department of Cell and Molecular Sciences, The James Hutton Institute, Dundee, United Kingdom
| | - Ramesh Raju Vetukuri
- Department of Plant Breeding, Horticum, Swedish University of Agricultural Sciences, Lomma, Sweden
- *Correspondence: Ramesh Raju Vetukuri, ; Mukesh Dubey,
| | - Mukesh Dubey
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
- *Correspondence: Ramesh Raju Vetukuri, ; Mukesh Dubey,
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9
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GLH/VASA helicases promote germ granule formation to ensure the fidelity of piRNA-mediated transcriptome surveillance. Nat Commun 2022; 13:5306. [PMID: 36085149 PMCID: PMC9463143 DOI: 10.1038/s41467-022-32880-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 08/22/2022] [Indexed: 11/16/2022] Open
Abstract
piRNAs function as guardians of the genome by silencing non-self nucleic acids and transposable elements in animals. Many piRNA factors are enriched in perinuclear germ granules, but whether their localization is required for piRNA biogenesis or function is not known. Here we show that GLH/VASA helicase mutants exhibit defects in forming perinuclear condensates containing PIWI and other small RNA cofactors. These mutant animals produce largely normal levels of piRNA but are defective in triggering piRNA silencing. Strikingly, while many piRNA targets are activated in GLH mutants, we observe that hundreds of endogenous genes are aberrantly silenced by piRNAs. This defect in self versus non-self recognition is also observed in other mutants where perinuclear germ granules are disrupted. Together, our results argue that perinuclear germ granules function critically to promote the fidelity of piRNA-based transcriptome surveillance in C. elegans and preserve self versus non-self distinction. Phase separated, membrane-less germ granules preserve fertility and cellular function in animal germ cells. Here the authors show that loss of germ granules impacts piRNA pathway fidelity in the recognition of self and non-self nucleic acids.
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10
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Gajic Z, Kaur D, Ni J, Zhu Z, Zhebrun A, Gajic M, Kim M, Hong J, Priyadarshini M, Frøkjær-Jensen C, Gu S. Target-dependent suppression of siRNA production modulates the levels of endogenous siRNAs in the Caenorhabditis elegans germline. Development 2022; 149:dev200692. [PMID: 35876680 PMCID: PMC9481970 DOI: 10.1242/dev.200692] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 07/14/2022] [Indexed: 08/24/2023]
Abstract
Despite the prominent role of endo-siRNAs in transposon silencing, their expression is not limited to these 'nonself' DNA elements. Transcripts of protein-coding genes ('self' DNA) in some cases also produce endo-siRNAs in yeast, plants and animals. How cells distinguish these two populations of siRNAs to prevent unwanted silencing of active genes in animals is not well understood. To address this question, we inserted various self-gene or gfp fragments into an LTR retrotransposon that produces abundant siRNAs and examined the propensity of these gene fragments to produce ectopic siRNAs in the Caenorhabditis elegans germline. We found that fragments of germline genes are generally protected from production of ectopic siRNAs. This phenomenon, which we termed 'target-directed suppression of siRNA production' (or siRNA suppression), is dependent on the germline expression of target mRNA and requires germline P-granule components. We found that siRNA suppression can also occur in naturally produced endo-siRNAs. We suggest that siRNA suppression plays an important role in regulating siRNA expression and preventing self-genes from aberrant epigenetic silencing. This article has an associated 'The people behind the papers' interview.
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Affiliation(s)
- Zoran Gajic
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Diljeet Kaur
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Julie Ni
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Zhaorong Zhu
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Anna Zhebrun
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Maria Gajic
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Matthew Kim
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Julia Hong
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Monika Priyadarshini
- Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955–6900, Kingdom of Saudi Arabia
| | - Christian Frøkjær-Jensen
- Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955–6900, Kingdom of Saudi Arabia
| | - Sam Gu
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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11
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Comparative Small RNA and Degradome Sequencing Provides Insights into Antagonistic Interactions in the Biocontrol Fungus Clonostachys rosea. Appl Environ Microbiol 2022; 88:e0064322. [PMID: 35695572 PMCID: PMC9275246 DOI: 10.1128/aem.00643-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Necrotrophic mycoparasitism is an intricate process involving recognition, physical mycelial contact, and killing of host fungi (mycohosts). During such interactions, mycoparasites undergo a complex developmental process involving massive regulatory changes of gene expression to produce a range of chemical compounds and proteins that contribute to the parasitism of the mycohosts. Small RNAs (sRNAs) are vital components of posttranscriptional gene regulation, although their role in gene expression regulation during mycoparasitisms remain understudied. Here, we investigated the role of sRNA-mediated gene regulation in mycoparasitism by performing sRNA and degradome tag sequencing of the mycoparasitic fungus Clonostachys rosea interacting with the plant-pathogenic mycohosts Botrytis cinerea and Fusarium graminearum at two time points. The majority of differentially expressed sRNAs were downregulated during the interactions with the mycohosts compared to a C. rosea self-interaction control, thus allowing desuppression (upregulation) of mycohost-responsive genes. Degradome analysis showed a positive correlation between high degradome counts and antisense sRNA mapping and led to the identification of 201 sRNA-mediated potential gene targets for 282 differentially expressed sRNAs. Analysis of sRNA potential gene targets revealed that the regulation of genes coding for membrane proteins was a common response against both mycohosts. The regulation of genes involved in oxidative stress tolerance and cellular metabolic and biosynthetic processes was exclusive against F. graminearum, highlighting common and mycohost-specific gene regulation of C. rosea. By combining these results with transcriptome data collected during a previous study, we expand the understanding of the role of sRNA in regulating interspecific fungal interactions and mycoparasitism. IMPORTANCE Small RNAs (sRNAs) are emerging as key players in pathogenic and mutualistic fungus-plant interactions; however, their role in fungus-fungus interactions remains elusive. In this study, we employed the necrotrophic mycoparasite Clonostachys rosea and the plant-pathogenic mycohosts Botrytis cinerea and Fusarium graminearum and investigated the sRNA-mediated gene regulation in mycoparasitic interactions. The combined approach of sRNA and degradome tag sequencing identified 201 sRNA-mediated putative gene targets for 282 differentially expressed sRNAs, highlighting the role of sRNA-mediated regulation of mycoparasitism in C. rosea. We also identified 36 known and 13 novel microRNAs (miRNAs) and their potential gene targets at the endogenous level and at a cross-species level in B. cinerea and F. graminearum, indicating a role of cross-species RNA interference (RNAi) in mycoparasitism, representing a novel mechanism in biocontrol interactions. Furthermore, we showed that C. rosea adapts its transcriptional response, and thereby its interaction mechanisms, based on the interaction stages and identity of the mycohost.
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12
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Pastore B, Hertz HL, Tang W. Comparative analysis of piRNA sequences, targets and functions in nematodes. RNA Biol 2022; 19:1276-1292. [PMID: 36412988 PMCID: PMC9683057 DOI: 10.1080/15476286.2022.2149170] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Piwi proteins and Piwi-interacting RNAs (piRNAs) are best known for their roles in suppressing transposons and promoting fertility. Yet piRNA biogenesis and its mechanisms of action differ widely between distantly related species. To better understand the evolution of piRNAs, we characterized the piRNA pathway in C. briggsae, a sibling species of the model organism C. elegans. Our analyses define 25,883 piRNA producing-loci in C. briggsae. piRNA sequences in C. briggsae are extremely divergent from their counterparts in C. elegans, yet both species adopt similar genomic organization that drive piRNA expression. By examining production of Piwi-mediated secondary small RNAs, we identified a set of protein-coding genes that are evolutionarily conserved piRNA targets. In contrast to C. elegans, small RNAs targeting ribosomal RNAs or histone transcripts are not hyper-accumulated in C. briggsae Piwi mutants. Instead, we found that transcripts with few introns are prone to small RNA overamplification. Together our work highlights evolutionary conservation and divergence of the nematode piRNA pathway and provides insights into its role in endogenous gene regulation.
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Affiliation(s)
- Benjamin Pastore
- Department of Biological Chemistry and Pharmacology, The Ohio State University,Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA,Center for RNA Biology, Ohio State University, Columbus, OH, USA
| | - Hannah L. Hertz
- Department of Biological Chemistry and Pharmacology, The Ohio State University,Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA
| | - Wen Tang
- Department of Biological Chemistry and Pharmacology, The Ohio State University,Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA,CONTACT Wen Tang Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA
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13
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Abstract
DNA is central to the propagation and evolution of most living organisms due to the essential process of its self-replication. Yet it also encodes factors that permit epigenetic (not included in DNA sequence) flow of information from parents to their offspring and beyond. The known mechanisms of epigenetic inheritance include chemical modifications of DNA and chromatin, as well as regulatory RNAs. All these factors can modulate gene expression programs in the ensuing generations. The nematode Caenorhabditis elegans is recognized as a pioneer organism in transgenerational epigenetic inheritance research. Recent advances in C. elegans epigenetics include the discoveries of control mechanisms that limit the duration of RNA-based epigenetic inheritance, periodic DNA motifs that counteract epigenetic silencing establishment, new mechanistic insights into epigenetic inheritance carried by sperm, and the tantalizing examples of inheritance of sensory experiences. This review aims to highlight new findings in epigenetics research in C. elegans with the main focus on transgenerational epigenetic phenomena dependent on small RNAs.
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Affiliation(s)
- Alla Grishok
- Department of Biochemistry, BU Genome Science Institute, Boston University School of Medicine, 72 E. Concord St. K422, Boston, MA 02118, USA
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14
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Pastore B, Hertz HL, Price IF, Tang W. pre-piRNA trimming and 2'-O-methylation protect piRNAs from 3' tailing and degradation in C. elegans. Cell Rep 2021; 36:109640. [PMID: 34469728 PMCID: PMC8459939 DOI: 10.1016/j.celrep.2021.109640] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 06/24/2021] [Accepted: 08/10/2021] [Indexed: 11/30/2022] Open
Abstract
The Piwi-interacting RNA (piRNA) pathway suppresses transposable elements and promotes fertility in diverse organisms. Maturation of piRNAs involves pre-piRNA trimming followed by 2'-O-methylation at their 3' termini. Here, we report that the 3' termini of Caenorhabditis elegans piRNAs are subject to nontemplated nucleotide addition, and piRNAs with 3' addition exhibit extensive base-pairing interaction with their target RNAs. Animals deficient for PARN-1 (pre-piRNA trimmer) and HENN-1 (2'-O-methyltransferase) accumulate piRNAs with 3' nontemplated nucleotides. In henn-1 mutants, piRNAs are shortened prior to 3' addition, whereas long isoforms of untrimmed piRNAs are preferentially modified in parn-1 mutant animals. Loss of either PARN-1 or HENN-1 results in modest reduction in steady-state levels of piRNAs. Deletion of both enzymes leads to depletion of piRNAs, desilenced piRNA targets, and impaired fecundity. Together, our findings suggest that pre-piRNA trimming and 2'-O-methylation act collaboratively to protect piRNAs from tailing and degradation.
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Affiliation(s)
- Benjamin Pastore
- Department of Biological Chemistry and Pharmacology, Columbus, OH 43210, USA; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA; Ohio State Biochemistry Program, Columbus, OH 43210, USA
| | - Hannah L Hertz
- Department of Biological Chemistry and Pharmacology, Columbus, OH 43210, USA; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Ian F Price
- Department of Biological Chemistry and Pharmacology, Columbus, OH 43210, USA; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA; Ohio State Biochemistry Program, Columbus, OH 43210, USA
| | - Wen Tang
- Department of Biological Chemistry and Pharmacology, Columbus, OH 43210, USA; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.
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15
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Wahba L, Hansen L, Fire AZ. An essential role for the piRNA pathway in regulating the ribosomal RNA pool in C. elegans. Dev Cell 2021; 56:2295-2312.e6. [PMID: 34388368 PMCID: PMC8387450 DOI: 10.1016/j.devcel.2021.07.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 06/11/2021] [Accepted: 07/15/2021] [Indexed: 01/08/2023]
Abstract
Piwi-interacting RNAs (piRNAs) are RNA effectors with key roles in maintaining genome integrity and promoting fertility in metazoans. In Caenorhabditis elegans loss of piRNAs leads to a transgenerational sterility phenotype. The plethora of piRNAs and their ability to silence transcripts with imperfect complementarity have raised several (non-exclusive) models for the underlying drivers of sterility. Here, we report the extranuclear and transferable nature of the sterility driver, its suppression via mutations disrupting the endogenous RNAi and poly-uridylation machinery, and copy-number amplification at the ribosomal DNA locus. In piRNA-deficient animals, several small interfering RNA (siRNA) populations become increasingly overabundant in the generations preceding loss of germline function, including ribosomal siRNAs (risiRNAs). A concomitant increase in uridylated sense rRNA fragments suggests that poly-uridylation may potentiate RNAi-mediated gene silencing of rRNAs. We conclude that loss of the piRNA machinery allows for unchecked amplification of siRNA populations, originating from abundant highly structured RNAs, to deleterious levels.
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Affiliation(s)
- Lamia Wahba
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Loren Hansen
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Andrew Z Fire
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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16
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Singh M, Cornes E, Li B, Quarato P, Bourdon L, Dingli F, Loew D, Proccacia S, Cecere G. Translation and codon usage regulate Argonaute slicer activity to trigger small RNA biogenesis. Nat Commun 2021; 12:3492. [PMID: 34108460 PMCID: PMC8190271 DOI: 10.1038/s41467-021-23615-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 05/06/2021] [Indexed: 11/08/2022] Open
Abstract
In the Caenorhabditis elegans germline, thousands of mRNAs are concomitantly expressed with antisense 22G-RNAs, which are loaded into the Argonaute CSR-1. Despite their essential functions for animal fertility and embryonic development, how CSR-1 22G-RNAs are produced remains unknown. Here, we show that CSR-1 slicer activity is primarily involved in triggering the synthesis of small RNAs on the coding sequences of germline mRNAs and post-transcriptionally regulates a fraction of targets. CSR-1-cleaved mRNAs prime the RNA-dependent RNA polymerase, EGO-1, to synthesize 22G-RNAs in phase with translating ribosomes, in contrast to other 22G-RNAs mostly synthesized in germ granules. Moreover, codon optimality and efficient translation antagonize CSR-1 slicing and 22G-RNAs biogenesis. We propose that codon usage differences encoded into mRNA sequences might be a conserved strategy in eukaryotes to regulate small RNA biogenesis and Argonaute targeting.
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Affiliation(s)
- Meetali Singh
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR3738, CNRS, Paris, France
| | - Eric Cornes
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR3738, CNRS, Paris, France
| | - Blaise Li
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR3738, CNRS, Paris, France
- Hub de Bioinformatique et Biostatistique-Département Biologie Computationnelle, Institut Pasteur, Paris, France
| | - Piergiuseppe Quarato
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR3738, CNRS, Paris, France
- Sorbonne Université, Collège Doctoral, Paris, France
| | - Loan Bourdon
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR3738, CNRS, Paris, France
| | - Florent Dingli
- Institut Curie, PSL Research University, Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Paris, France
| | - Damarys Loew
- Institut Curie, PSL Research University, Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Paris, France
| | - Simone Proccacia
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR3738, CNRS, Paris, France
- Università di Trento, Trento TN, Italy
| | - Germano Cecere
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR3738, CNRS, Paris, France.
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17
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Huang X, Wong G. An old weapon with a new function: PIWI-interacting RNAs in neurodegenerative diseases. Transl Neurodegener 2021; 10:9. [PMID: 33685517 PMCID: PMC7938595 DOI: 10.1186/s40035-021-00233-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 02/16/2021] [Indexed: 12/16/2022] Open
Abstract
PIWI-interacting RNAs (piRNAs) are small non-coding transcripts that are highly conserved across species and regulate gene expression through pre- and post-transcriptional processes. piRNAs were originally discovered in germline cells and protect against transposable element expression to promote and maintain genome stability. In the recent decade, emerging roles of piRNAs have been revealed, including the roles in sterility, tumorigenesis, metabolic homeostasis, neurodevelopment, and neurodegenerative diseases. In this review, we summarize piRNA biogenesis in C. elegans, Drosophila, and mice, and further elaborate upon how piRNAs mitigate the harmful effects of transposons. Lastly, the most recent findings on piRNA participation in neurological diseases are highlighted. We speculate on the mechanisms of piRNA action in the development and progression of neurodegenerative diseases. Understanding the roles of piRNAs in neurological diseases may facilitate their applications in diagnostic and therapeutic practice.
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Affiliation(s)
- Xiaobing Huang
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Macau, 999078, S.A.R., China
| | - Garry Wong
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Macau, 999078, S.A.R., China.
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18
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Abstract
A diversity of gene regulatory mechanisms drives the changes in gene expression required for animal development. Here, we discuss the developmental roles of a class of gene regulatory factors composed of a core protein subunit of the Argonaute family and a 21-26-nucleotide RNA cofactor. These represent ancient regulatory complexes, originally evolved to repress genomic parasites such as transposons, viruses and retroviruses. However, over the course of evolution, small RNA-guided pathways have expanded and diversified, and they play multiple roles across all eukaryotes. Pertinent to this review, Argonaute and small RNA-mediated regulation has acquired numerous functions that affect all aspects of animal life. The regulatory function is provided by the Argonaute protein and its interactors, while the small RNA provides target specificity, guiding the Argonaute to a complementary RNA. C. elegans has 19 different, functional Argonautes, defining distinct yet interconnected pathways. Each Argonaute binds a relatively well-defined class of small RNA with distinct molecular properties. A broad classification of animal small RNA pathways distinguishes between two groups: (i) the microRNA pathway is involved in repressing relatively specific endogenous genes and (ii) the other small RNA pathways, which effectively act as a genomic immune system to primarily repress expression of foreign or "non-self" RNA while maintaining correct endogenous gene expression. microRNAs play prominent direct roles in all developmental stages, adult physiology and lifespan. The other small RNA pathways act primarily in the germline, but their impact extends far beyond, into embryogenesis and adult physiology, and even to subsequent generations. Here, we review the mechanisms and developmental functions of the diverse small RNA pathways of C. elegans.
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Affiliation(s)
| | - Luisa Cochella
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria.
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19
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Karunanithi S, Oruganti V, Marker S, Rodriguez-Viana AM, Drews F, Pirritano M, Nordström K, Simon M, Schulz MH. Exogenous RNAi mechanisms contribute to transcriptome adaptation by phased siRNA clusters in Paramecium. Nucleic Acids Res 2019; 47:8036-8049. [PMID: 31251800 PMCID: PMC6735861 DOI: 10.1093/nar/gkz553] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Revised: 06/06/2019] [Accepted: 06/19/2019] [Indexed: 01/26/2023] Open
Abstract
Extensive research has characterized distinct exogenous RNAi pathways interfering in gene expression during vegetative growth of the unicellular model ciliate Paramecium. However, role of RNAi in endogenous transcriptome regulation, and environmental adaptation is unknown. Here, we describe the first genome-wide profiling of endogenous sRNAs in context of different transcriptomic states (serotypes). We developed a pipeline to identify, and characterize 2602 siRNA producing clusters (SRCs). Our data show no evidence that SRCs produce miRNAs, and in contrast to other species, no preference for strand specificity of siRNAs. Interestingly, most SRCs overlap coding genes and a separate group show siRNA phasing along the entire open reading frame, suggesting that the mRNA transcript serves as a source for siRNAs. Integrative analysis of siRNA abundance and gene expression levels revealed surprisingly that mRNA and siRNA show negative as well as positive associations. Two RNA-dependent RNA Polymerase mutants, RDR1 and RDR2, show a drastic loss of siRNAs especially in phased SRCs accompanied with increased mRNA levels. Importantly, most SRCs depend on both RDRs, reminiscent to primary siRNAs in the RNAi against exogenous RNA, indicating mechanistic overlaps between exogenous and endogenous RNAi contributing to flexible transcriptome adaptation.
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Affiliation(s)
- Sivarajan Karunanithi
- Cluster of Excellence, Multimodal Computing and Interaction, Saarland University and Department for Computational Biology and Applied Algorithmics, Max Planck Institute for Informatics, Saarland Informatics Campus, 66123 Saarbrücken, Germany.,Graduate School of Computer Science, Saarland Informatics Campus, 66123 Saarbrücken, Germany.,Institute for Cardiovascular Regeneration, Goethe-University Hospital, 60590 Frankfurt, Germany
| | - Vidya Oruganti
- Cluster of Excellence, Multimodal Computing and Interaction, Saarland University and Department for Computational Biology and Applied Algorithmics, Max Planck Institute for Informatics, Saarland Informatics Campus, 66123 Saarbrücken, Germany
| | - Simone Marker
- Molecular Cell Dynamics, Centre for Human and Molecular Biology, Saarland University, 66123 Saarbrücken, Germany
| | - Angela M Rodriguez-Viana
- Molecular Cell Dynamics, Centre for Human and Molecular Biology, Saarland University, 66123 Saarbrücken, Germany
| | - Franziska Drews
- Molecular Cell Dynamics, Centre for Human and Molecular Biology, Saarland University, 66123 Saarbrücken, Germany.,Molecular Cell Biology and Microbiology, Wuppertal University, 42097 Wuppertal, Germany
| | - Marcello Pirritano
- Molecular Cell Dynamics, Centre for Human and Molecular Biology, Saarland University, 66123 Saarbrücken, Germany.,Molecular Cell Biology and Microbiology, Wuppertal University, 42097 Wuppertal, Germany
| | - Karl Nordström
- Genetics/Epigenetics, Centre for Human and Molecular Biology, Saarland University, 66123 Saarbrücken, Germany
| | - Martin Simon
- Molecular Cell Dynamics, Centre for Human and Molecular Biology, Saarland University, 66123 Saarbrücken, Germany.,Molecular Cell Biology and Microbiology, Wuppertal University, 42097 Wuppertal, Germany
| | - Marcel H Schulz
- Cluster of Excellence, Multimodal Computing and Interaction, Saarland University and Department for Computational Biology and Applied Algorithmics, Max Planck Institute for Informatics, Saarland Informatics Campus, 66123 Saarbrücken, Germany.,Institute for Cardiovascular Regeneration, Goethe-University Hospital, 60590 Frankfurt, Germany
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20
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Ravikumar S, Devanapally S, Jose AM. Gene silencing by double-stranded RNA from C. elegans neurons reveals functional mosaicism of RNA interference. Nucleic Acids Res 2019; 47:10059-10071. [PMID: 31501873 PMCID: PMC6821342 DOI: 10.1093/nar/gkz748] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/12/2019] [Accepted: 08/20/2019] [Indexed: 12/12/2022] Open
Abstract
Delivery of double-stranded RNA (dsRNA) into animals can silence genes of matching sequence in diverse cell types through mechanisms that have been collectively called RNA interference. In the nematode Caenorhabditis elegans, dsRNA from multiple sources can trigger the amplification of silencing signals. Amplification occurs through the production of small RNAs by two RNA-dependent RNA polymerases (RdRPs) that are thought to be tissue-specific - EGO-1 in the germline and RRF-1 in somatic cells. Here we demonstrate that EGO-1 can compensate for the lack of RRF-1 when dsRNA from neurons is used to silence genes in intestinal cells. However, the lineal origins of cells that can use EGO-1 varies. This variability could be because random sets of cells can either receive different amounts of dsRNA from the same source or use different RdRPs to perform the same function. Variability is masked in wild-type animals, which show extensive silencing by neuronal dsRNA. As a result, cells appear similarly functional despite underlying differences that vary from animal to animal. This functional mosaicism cautions against inferring uniformity of mechanism based on uniformity of outcome. We speculate that functional mosaicism could contribute to escape from targeted therapies and could allow developmental systems to drift over evolutionary time.
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Affiliation(s)
- Snusha Ravikumar
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Sindhuja Devanapally
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Antony M Jose
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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21
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Lev I, Toker IA, Mor Y, Nitzan A, Weintraub G, Antonova O, Bhonkar O, Ben Shushan I, Seroussi U, Claycomb JM, Anava S, Gingold H, Zaidel-Bar R, Rechavi O. Germ Granules Govern Small RNA Inheritance. Curr Biol 2019; 29:2880-2891.e4. [PMID: 31378614 PMCID: PMC6739422 DOI: 10.1016/j.cub.2019.07.054] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 07/01/2019] [Accepted: 07/17/2019] [Indexed: 02/04/2023]
Abstract
In C. elegans nematodes, components of liquid-like germ granules were shown to be required for transgenerational small RNA inheritance. Surprisingly, we show here that mutants with defective germ granules can nevertheless inherit potent small RNA-based silencing responses, but some of the mutants lose this ability after many generations of homozygosity. Animals mutated in pptr-1, which is required for stabilization of P granules in the early embryo, display extraordinarily strong heritable RNAi responses, lasting for tens of generations. Intriguingly, the RNAi capacity of descendants derived from mutants defective in the core germ granule proteins MEG-3 and MEG-4 is determined by the genotype of the ancestors and changes transgenerationally. Further, whether the meg-3/4 mutant alleles were present in the paternal or maternal lineages leads to different transgenerational consequences. Small RNA inheritance, rather than maternal contribution of the germ granules themselves, mediates the transgenerational defects in RNAi of meg-3/4 mutants and their progeny. Accordingly, germ granule defects lead to heritable genome-wide mis-expression of endogenous small RNAs. Upon disruption of germ granules, hrde-1 mutants can inherit RNAi, although HRDE-1 was previously thought to be absolutely required for RNAi inheritance. We propose that germ granules sort and shape the RNA pool, and that small RNA inheritance maintains this activity for multiple generations.
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Affiliation(s)
- Itamar Lev
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Itai Antoine Toker
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Yael Mor
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Anat Nitzan
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Guy Weintraub
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Olga Antonova
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ornit Bhonkar
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Itay Ben Shushan
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Uri Seroussi
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Julie M Claycomb
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Sarit Anava
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Hila Gingold
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ronen Zaidel-Bar
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Oded Rechavi
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel.
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22
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Xu Y, Borcherding AF, Heier C, Tian G, Roeder T, Kühnlein RP. Chronic dysfunction of Stromal interaction molecule by pulsed RNAi induction in fat tissue impairs organismal energy homeostasis in Drosophila. Sci Rep 2019; 9:6989. [PMID: 31061470 PMCID: PMC6502815 DOI: 10.1038/s41598-019-43327-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 04/15/2019] [Indexed: 01/09/2023] Open
Abstract
Obesity is a progressive, chronic disease, which can be caused by long-term miscommunication between organs. It remains challenging to understand how chronic dysfunction in a particular tissue remotely impairs other organs to eventually imbalance organismal energy homeostasis. Here we introduce RNAi Pulse Induction (RiPI) mediated by short hairpin RNA (shRiPI) or double-stranded RNA (dsRiPI) to generate chronic, organ-specific gene knockdown in the adult Drosophila fat tissue. We show that organ-restricted RiPI targeting Stromal interaction molecule (Stim), an essential factor of store-operated calcium entry (SOCE), results in progressive fat accumulation in fly adipose tissue. Chronic SOCE-dependent adipose tissue dysfunction manifests in considerable changes of the fat cell transcriptome profile, and in resistance to the glucagon-like Adipokinetic hormone (Akh) signaling. Remotely, the adipose tissue dysfunction promotes hyperphagia likely via increased secretion of Akh from the neuroendocrine system. Collectively, our study presents a novel in vivo paradigm in the fly, which is widely applicable to model and functionally analyze inter-organ communication processes in chronic diseases.
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Affiliation(s)
- Yanjun Xu
- Max-Planck-Institut für biophysikalische Chemie, Research Group Molecular Physiology, Am Faβberg 11, D-37077, Göttingen, Germany.
- Max-Planck-Institut für biophysikalische Chemie, Department of Molecular Developmental Biology, Am Faβberg 11, D-37077, Göttingen, Germany.
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, D-85764, Neuherberg, München, Germany.
| | - Annika F Borcherding
- Max-Planck-Institut für biophysikalische Chemie, Research Group Molecular Physiology, Am Faβberg 11, D-37077, Göttingen, Germany
| | - Christoph Heier
- University of Graz, Institute of Molecular Biosciences, Humboldtstrasse 50/2.OG, A-8010, Graz, Austria
| | - Gu Tian
- Christian-Albrechts University Kiel, Zoology, Molecular Physiology, 24098, Kiel, Germany
- Airway Research Center North (ARCN), Member of the German Center for Lung Research (DZL), Kiel, Germany
| | - Thomas Roeder
- Christian-Albrechts University Kiel, Zoology, Molecular Physiology, 24098, Kiel, Germany
- Airway Research Center North (ARCN), Member of the German Center for Lung Research (DZL), Kiel, Germany
| | - Ronald P Kühnlein
- Max-Planck-Institut für biophysikalische Chemie, Research Group Molecular Physiology, Am Faβberg 11, D-37077, Göttingen, Germany.
- University of Graz, Institute of Molecular Biosciences, Humboldtstrasse 50/2.OG, A-8010, Graz, Austria.
- BioTechMed Graz, Graz, Austria.
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23
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Lev I, Gingold H, Rechavi O. H3K9me3 is required for inheritance of small RNAs that target a unique subset of newly evolved genes. eLife 2019; 8:e40448. [PMID: 30869075 PMCID: PMC6417860 DOI: 10.7554/elife.40448] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 02/26/2019] [Indexed: 12/17/2022] Open
Abstract
In Caenorhabditis elegans, RNA interference (RNAi) responses can transmit across generations via small RNAs. RNAi inheritance is associated with Histone-3-Lysine-9 tri-methylation (H3K9me3) of the targeted genes. In other organisms, maintenance of silencing requires a feed-forward loop between H3K9me3 and small RNAs. Here, we show that in C. elegans not only is H3K9me3 unnecessary for inheritance, the modification's function depends on the identity of the RNAi-targeted gene. We found an asymmetry in the requirement for H3K9me3 and the main worm H3K9me3 methyltransferases, SET-25 and SET-32. Both methyltransferases promote heritable silencing of the foreign gene gfp, but are dispensable for silencing of the endogenous gene oma-1. Genome-wide examination of heritable endogenous small interfering RNAs (endo-siRNAs) revealed that endo-siRNAs that depend on SET-25 and SET-32 target newly acquired and highly H3K9me3 marked genes. Thus, 'repressive' chromatin marks could be important specifically for heritable silencing of genes which are flagged as 'foreign', such as gfp. Editorial note This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
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Affiliation(s)
- Itamar Lev
- Department of Neurobiology, Wise Faculty of Life Sciences & Sagol School of NeuroscienceTel Aviv UniversityTel AvivIsrael
| | - Hila Gingold
- Department of Neurobiology, Wise Faculty of Life Sciences & Sagol School of NeuroscienceTel Aviv UniversityTel AvivIsrael
| | - Oded Rechavi
- Department of Neurobiology, Wise Faculty of Life Sciences & Sagol School of NeuroscienceTel Aviv UniversityTel AvivIsrael
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24
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Almeida MV, de Jesus Domingues AM, Ketting RF. Maternal and zygotic gene regulatory effects of endogenous RNAi pathways. PLoS Genet 2019; 15:e1007784. [PMID: 30759082 PMCID: PMC6391025 DOI: 10.1371/journal.pgen.1007784] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 02/26/2019] [Accepted: 01/23/2019] [Indexed: 11/30/2022] Open
Abstract
Endogenous small RNAs (sRNAs) and Argonaute proteins are ubiquitous regulators of gene expression in germline and somatic tissues. sRNA-Argonaute complexes are often expressed in gametes and are consequently inherited by the next generation upon fertilization. In Caenorhabditis elegans, 26G-RNAs are primary endogenous sRNAs that trigger the expression of downstream secondary sRNAs. Two subpopulations of 26G-RNAs exist, each of which displaying strongly compartmentalized expression: one is expressed in the spermatogenic gonad and associates with the Argonautes ALG-3/4; plus another expressed in oocytes and in embryos, which associates with the Argonaute ERGO-1. The determinants and dynamics of gene silencing elicited by 26G-RNAs are largely unknown. Here, we provide diverse new insights into these endogenous sRNA pathways of C. elegans. Using genetics and deep sequencing, we dissect a maternal effect of the ERGO-1 branch of the 26G-RNA pathway. We find that maternal primary sRNAs can trigger the production of zygotic secondary sRNAs that are able to silence targets, even in the absence of zygotic primary triggers. Thus, the interaction of maternal and zygotic sRNA populations, assures target gene silencing throughout animal development. Furthermore, we explore other facets of 26G-RNA biology related to the ALG-3/4 branch. We find that sRNA abundance, sRNA pattern of origin and the 3’ UTR length of target transcripts are predictors of the regulatory outcome by the Argonautes ALG-3/4. Lastly, we provide evidence suggesting that ALG-3 and ALG-4 regulate their own mRNAs in a negative feedback loop. Altogether, we provide several new regulatory insights on the dynamics, target regulation and self-regulation of the endogenous RNAi pathways of C. elegans. Small RNAs (sRNAs) and their partner Argonaute proteins regulate the expression of target RNAs. When sperm and egg meet upon fertilization, a diverse set of proteins and RNA, including sRNA-Argonaute complexes, is passed on to the developing progeny. Thus, these two players are important to initiate specific gene expression programs in the next generation. The nematode Caenorhabditis elegans expresses several classes of sRNAs. 26G-RNAs are a particular class of sRNAs that are divided into two subpopulations: one expressed in the spermatogenic gonad and another expressed in oocytes and in embryos. In this work, we describe the dynamics whereby oogenic 26G-RNAs setup gene silencing in the next generation. In addition, we show several ways that spermatogenic 26G-RNAs and their partner Argonautes, ALG-3 and ALG-4, use to regulate their targets. Finally, we show that ALG-3 and ALG-4 are fine-tuning their own expression, a rare role of Argonaute proteins. Overall, we provide new insights into how sRNAs and Argonautes are regulating gene expression.
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Affiliation(s)
- Miguel Vasconcelos Almeida
- Biology of Non-coding RNA Group, Institute of Molecular Biology, Ackermannweg 4, Mainz, Germany
- International PhD Programme on Gene Regulation, Epigenetics & Genome Stability, Mainz, Germany
| | | | - René F. Ketting
- Biology of Non-coding RNA Group, Institute of Molecular Biology, Ackermannweg 4, Mainz, Germany
- * E-mail:
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25
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Ni JZ, Kalinava N, Mendoza SG, Gu SG. The spatial and temporal dynamics of nuclear RNAi-targeted retrotransposon transcripts in Caenorhabditis elegans. Development 2018; 145:dev167346. [PMID: 30254142 PMCID: PMC6215403 DOI: 10.1242/dev.167346] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 09/17/2018] [Indexed: 02/03/2023]
Abstract
Nuclear RNA interference provides a unique approach to the study of RNA-mediated transgenerational epigenetic inheritance. A paradox in the field is that expression of target loci is necessary for the initiation and maintenance of their silencing. How expression and repression are coordinated during animal development is poorly understood. To resolve this gap, we took imaging, deep-sequencing and genetic approaches towards delineating the developmental regulation and subcellular localization of RNA transcripts of two representative endogenous targets, the LTR retrotransposons Cer3 and Cer8. By examining wild-type worms and a collection of mutant strains, we found that the expression and silencing cycle of Cer3 and Cer8 is coupled with embryonic and germline development. Strikingly, endogenous targets exhibit a hallmark of nuclear enrichment of their RNA transcripts. In addition, germline and somatic repressions of Cer3 have different genetic requirements for three heterochromatin enzymes, MET-2, SET-25 and SET-32, in conjunction with the nuclear Argonaute protein HRDE-1. These results provide the first comprehensive cellular and developmental characterization of nuclear RNAi activities throughout the animal reproductive cycle.
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Affiliation(s)
- Julie Zhouli Ni
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Natallia Kalinava
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Sofia Galindo Mendoza
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Sam Guoping Gu
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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26
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Xu F, Guang S, Feng X. Distinct nuclear and cytoplasmic machineries cooperatively promote the inheritance of RNAi in Caenorhabditis elegans. Biol Cell 2018; 110:217-224. [PMID: 30132958 DOI: 10.1111/boc.201800031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/16/2018] [Accepted: 08/17/2018] [Indexed: 12/17/2022]
Abstract
Epigenetic information can be inherited over multiple generations, which is termed as transgenerational epigenetic inheritance (TEI). Although the mechanism(s) of TEI remains poorly understood, noncoding RNAs have been demonstrated to play important roles in TEI. In many eukaryotes, double-stranded RNA (dsRNA) triggers the silencing of cellular nucleic acids that exhibit sequence homology to the dsRNA via a process termed RNA interference (RNAi). In Caenorhabditis elegans, dsRNA-directed gene silencing is heritable and can persist for a number of generations after its initial induction. During the process, small RNAs and the RNAi machinery mediate the initiation, transmission and re-establishment of the gene silencing state. In this review, we summarise our current understanding of the underlying mechanism(s) of transgenerational inheritance of RNAi in C. elegans and propose that multiple RNAi machineries may act cooperatively to promote TEI.
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Affiliation(s)
- Fei Xu
- Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China
| | - Shouhong Guang
- Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China
| | - Xuezhu Feng
- Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China
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27
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Rechavi O, Lev I. Principles of Transgenerational Small RNA Inheritance in Caenorhabditis elegans. Curr Biol 2018; 27:R720-R730. [PMID: 28743023 DOI: 10.1016/j.cub.2017.05.043] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Examples of transgenerational inheritance of environmental responses are rapidly accumulating. In Caenorhabditis elegans nematodes, such heritable information transmits across generations in the form of RNA-dependent RNA polymerase-amplified small RNAs. Regulatory small RNAs enable sequence-specific gene regulation, and unlike chromatin modifications, can move between tissues, and escape from immediate germline reprogramming. In this review, we discuss the path that small RNAs take from the soma to the germline, and elaborate on the mechanisms that maintain or erase parental small RNA responses after a specific number of generations. We focus on the intricate interactions between heritable small RNAs and histone modifications, deposited on specific loci. A trace of heritable chromatin marks, in particular trimethylation of histone H3 lysine 9, is deposited on RNAi-targeted loci. However, how these modifications regulate RNAi or small RNA inheritance was until recently unclear. Integrating the very latest literature, we suggest that changes to histone marks may instigate transgenerational gene regulation indirectly, by affecting the biogenesis of heritable small RNAs. Inheritance of small RNAs could spread adaptive ancestral responses.
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Affiliation(s)
- Oded Rechavi
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School for Neuroscience, Tel Aviv University, Tel Aviv, Israel 69978.
| | - Itamar Lev
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School for Neuroscience, Tel Aviv University, Tel Aviv, Israel 69978.
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28
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Weiser NE, Yang DX, Feng S, Kalinava N, Brown KC, Khanikar J, Freeberg MA, Snyder MJ, Csankovszki G, Chan RC, Gu SG, Montgomery TA, Jacobsen SE, Kim JK. MORC-1 Integrates Nuclear RNAi and Transgenerational Chromatin Architecture to Promote Germline Immortality. Dev Cell 2017; 41:408-423.e7. [PMID: 28535375 DOI: 10.1016/j.devcel.2017.04.023] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 04/05/2017] [Accepted: 04/25/2017] [Indexed: 12/12/2022]
Abstract
Germline-expressed endogenous small interfering RNAs (endo-siRNAs) transmit multigenerational epigenetic information to ensure fertility in subsequent generations. In Caenorhabditis elegans, nuclear RNAi ensures robust inheritance of endo-siRNAs and deposition of repressive H3K9me3 marks at target loci. How target silencing is maintained in subsequent generations is poorly understood. We discovered that morc-1 is essential for transgenerational fertility and acts as an effector of endo-siRNAs. Unexpectedly, morc-1 is dispensable for siRNA inheritance but is required for target silencing and maintenance of siRNA-dependent chromatin organization. A forward genetic screen identified mutations in met-1, which encodes an H3K36 methyltransferase, as potent suppressors of morc-1(-) and nuclear RNAi mutant phenotypes. Further analysis of nuclear RNAi and morc-1(-) mutants revealed a progressive, met-1-dependent enrichment of H3K36me3, suggesting that robust fertility requires repression of MET-1 activity at nuclear RNAi targets. Without MORC-1 and nuclear RNAi, MET-1-mediated encroachment of euchromatin leads to detrimental decondensation of germline chromatin and germline mortality.
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Affiliation(s)
- Natasha E Weiser
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Danny X Yang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Suhua Feng
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, PO Box 957239, Los Angeles, CA 90095-7239, USA; Eli and Edyth Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Natallia Kalinava
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Piscataway, NJ 08854, USA
| | - Kristen C Brown
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Jayshree Khanikar
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Mallory A Freeberg
- Department of Biology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Martha J Snyder
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Györgyi Csankovszki
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Raymond C Chan
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sam G Gu
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Piscataway, NJ 08854, USA
| | - Taiowa A Montgomery
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Steven E Jacobsen
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, PO Box 957239, Los Angeles, CA 90095-7239, USA; Eli and Edyth Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA 90095, USA; Howard Hughes Medical Institute, Los Angeles, CA 90095, USA.
| | - John K Kim
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109, USA; Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA; Department of Biology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
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29
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Fontenla S, Rinaldi G, Smircich P, Tort JF. Conservation and diversification of small RNA pathways within flatworms. BMC Evol Biol 2017; 17:215. [PMID: 28893179 PMCID: PMC5594548 DOI: 10.1186/s12862-017-1061-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 09/05/2017] [Indexed: 02/04/2023] Open
Abstract
Background Small non-coding RNAs, including miRNAs, and gene silencing mediated by RNA interference have been described in free-living and parasitic lineages of flatworms, but only few key factors of the small RNA pathways have been exhaustively investigated in a limited number of species. The availability of flatworm draft genomes and predicted proteomes allowed us to perform an extended survey of the genes involved in small non-coding RNA pathways in this phylum. Results Overall, findings show that the small non-coding RNA pathways are conserved in all the analyzed flatworm linages; however notable peculiarities were identified. While Piwi genes are amplified in free-living worms they are completely absent in all parasitic species. Remarkably all flatworms share a specific Argonaute family (FL-Ago) that has been independently amplified in different lineages. Other key factors such as Dicer are also duplicated, with Dicer-2 showing structural differences between trematodes, cestodes and free-living flatworms. Similarly, a very divergent GW182 Argonaute interacting protein was identified in all flatworm linages. Contrasting to this, genes involved in the amplification of the RNAi interfering signal were detected only in the ancestral free living species Macrostomum lignano. We here described all the putative small RNA pathways present in both free living and parasitic flatworm lineages. Conclusion These findings highlight innovations specifically evolved in platyhelminths presumably associated with novel mechanisms of gene expression regulation mediated by small RNA pathways that differ to what has been classically described in model organisms. Understanding these phylum-specific innovations and the differences between free living and parasitic species might provide clues to adaptations to parasitism, and would be relevant for gene-silencing technology development for parasitic flatworms that infect hundreds of million people worldwide. Electronic supplementary material The online version of this article (10.1186/s12862-017-1061-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Santiago Fontenla
- Departamento de Genética, Facultad de Medicina, Universidad de la República (UDELAR), Gral. Flores 2125, CP11800, Montevideo, MVD, Uruguay
| | - Gabriel Rinaldi
- Parasite Genomics, Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Pablo Smircich
- Departamento de Genética, Facultad de Medicina, Universidad de la República (UDELAR), Gral. Flores 2125, CP11800, Montevideo, MVD, Uruguay.,Laboratorio de Interacciones Moleculares, Facultad de Ciencias, Universidad de la República (UdelaR), Montevideo, Uruguay
| | - Jose F Tort
- Departamento de Genética, Facultad de Medicina, Universidad de la República (UDELAR), Gral. Flores 2125, CP11800, Montevideo, MVD, Uruguay.
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30
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Kalinava N, Ni JZ, Peterman K, Chen E, Gu SG. Decoupling the downstream effects of germline nuclear RNAi reveals that H3K9me3 is dispensable for heritable RNAi and the maintenance of endogenous siRNA-mediated transcriptional silencing in Caenorhabditis elegans. Epigenetics Chromatin 2017; 10:6. [PMID: 28228846 PMCID: PMC5311726 DOI: 10.1186/s13072-017-0114-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 02/08/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Germline nuclear RNAi in C. elegans is a transgenerational gene-silencing pathway that leads to H3K9 trimethylation (H3K9me3) and transcriptional silencing at the target genes. H3K9me3 induced by either exogenous double-stranded RNA (dsRNA) or endogenous siRNA (endo-siRNA) is highly specific to the target loci and transgenerationally heritable. Despite these features, the role of H3K9me3 in siRNA-mediated transcriptional silencing and inheritance of the silencing state at native target genes is unclear. In this study, we took combined genetic and whole-genome approaches to address this question. RESULTS Here we demonstrate that siRNA-mediated H3K9me3 requires combined activities of three H3K9 histone methyltransferases: MET-2, SET-25, and SET-32. set-32 single, met-2 set-25 double, and met-2 set-25;set-32 triple mutant adult animals all exhibit prominent reductions in H3K9me3 throughout the genome, with met-2 set-25;set-32 mutant worms losing all detectable H3K9me3 signals. Surprisingly, loss of high-magnitude H3K9me3 at the native nuclear RNAi targets has no effect on the transcriptional silencing state. In addition, the exogenous dsRNA-induced transcriptional silencing and heritable RNAi at oma-1, a well-established nuclear RNAi reporter gene, are completely resistant to the loss of H3K9me3. CONCLUSIONS Nuclear RNAi-mediated H3K9me3 in C. elegans requires multiple histone methyltransferases, including MET-2, SET-25, and SET-32. H3K9me3 is not essential for dsRNA-induced heritable RNAi or the maintenance of endo-siRNA-mediated transcriptional silencing in C. elegans. We propose that siRNA-mediated transcriptional silencing in C. elegans can be maintained by an H3K9me3-independent mechanism.
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Affiliation(s)
- Natallia Kalinava
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Piscataway, NJ 08854 USA
| | - Julie Zhouli Ni
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Piscataway, NJ 08854 USA
| | - Kimberly Peterman
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Piscataway, NJ 08854 USA
| | - Esteban Chen
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Piscataway, NJ 08854 USA
| | - Sam Guoping Gu
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Piscataway, NJ 08854 USA.,Nelson Labs A125, 604 Allison Road, Piscataway, NJ 08854 USA
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31
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Gerson-Gurwitz A, Wang S, Sathe S, Green R, Yeo GW, Oegema K, Desai A. A Small RNA-Catalytic Argonaute Pathway Tunes Germline Transcript Levels to Ensure Embryonic Divisions. Cell 2016; 165:396-409. [PMID: 27020753 DOI: 10.1016/j.cell.2016.02.040] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 01/20/2016] [Accepted: 02/18/2016] [Indexed: 12/11/2022]
Abstract
Multiple division cycles without growth are a characteristic feature of early embryogenesis. The female germline loads proteins and RNAs into oocytes to support these divisions, which lack many quality control mechanisms operating in somatic cells undergoing growth. Here, we describe a small RNA-Argonaute pathway that ensures early embryonic divisions in C. elegans by employing catalytic slicing activity to broadly tune, instead of silence, germline gene expression. Misregulation of one target, a kinesin-13 microtubule depolymerase, underlies a major phenotype associated with pathway loss. Tuning of target transcript levels is guided by the density of homologous small RNAs, whose generation must ultimately be related to target sequence. Thus, the tuning action of a small RNA-catalytic Argonaute pathway generates oocytes capable of supporting embryogenesis. We speculate that the specialized nature of germline chromatin led to the emergence of small RNA-catalytic Argonaute pathways in the female germline as a post-transcriptional control layer to optimize oocyte composition.
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Affiliation(s)
- Adina Gerson-Gurwitz
- Ludwig Institute for Cancer Research, San Diego, CA 92093, USA; Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Shaohe Wang
- Ludwig Institute for Cancer Research, San Diego, CA 92093, USA; Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA; Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, CA 92093, USA
| | - Shashank Sathe
- Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA; UCSD Stem Cell Program & Sanford Consortium for Regenerative Medicine, Institute for Genomic Medicine, La Jolla, CA 92093, USA
| | - Rebecca Green
- Ludwig Institute for Cancer Research, San Diego, CA 92093, USA; Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Gene W Yeo
- Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA; Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, CA 92093, USA; UCSD Stem Cell Program & Sanford Consortium for Regenerative Medicine, Institute for Genomic Medicine, La Jolla, CA 92093, USA
| | - Karen Oegema
- Ludwig Institute for Cancer Research, San Diego, CA 92093, USA; Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA; Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, CA 92093, USA
| | - Arshad Desai
- Ludwig Institute for Cancer Research, San Diego, CA 92093, USA; Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA; Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, CA 92093, USA.
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Houri-Ze’evi L, Korem Y, Sheftel H, Faigenbloom L, Toker IA, Dagan Y, Awad L, Degani L, Alon U, Rechavi O. A Tunable Mechanism Determines the Duration of the Transgenerational Small RNA Inheritance in C. elegans. Cell 2016; 165:88-99. [DOI: 10.1016/j.cell.2016.02.057] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 01/19/2016] [Accepted: 02/24/2016] [Indexed: 01/13/2023]
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Liew YJ, Ryu T, Aranda M, Ravasi T. miRNA Repertoires of Demosponges Stylissa carteri and Xestospongia testudinaria. PLoS One 2016; 11:e0149080. [PMID: 26871907 PMCID: PMC4752309 DOI: 10.1371/journal.pone.0149080] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Accepted: 01/26/2016] [Indexed: 11/23/2022] Open
Abstract
MicroRNAs (miRNAs) are small regulatory RNAs that are involved in many biological process in eukaryotes. They play a crucial role in modulating genetic expression of their targets, which makes them integral components of transcriptional regulatory networks. As sponges (phylum Porifera) are commonly considered the most basal metazoan, the in-depth capture of miRNAs from these organisms provides additional clues to the evolution of miRNA families in metazoans. Here, we identified the core proteins involved in the biogenesis of miRNAs, and obtained evidence for bona fide miRNA sequences for two marine sponges Stylissa carteri and Xestospongia testudinaria (11 and 19 respectively). Our analysis identified several miRNAs that are conserved amongst demosponges, and revealed that all of the novel miRNAs identified in these two species are specific to the class Demospongiae.
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Affiliation(s)
- Yi Jin Liew
- Division of Biological and Environmental Sciences & Engineering, King Abdullah University of Science and Technology, Thuwal, 23955–6900, Kingdom of Saudi Arabia
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, 23955–6900, Kingdom of Saudi Arabia
| | - Taewoo Ryu
- Division of Biological and Environmental Sciences & Engineering, King Abdullah University of Science and Technology, Thuwal, 23955–6900, Kingdom of Saudi Arabia
- KAUST Environmental Epigenetics Program (KEEP), King Abdullah University of Science and Technology, Thuwal, 23955–6900, Kingdom of Saudi Arabia
| | - Manuel Aranda
- Division of Biological and Environmental Sciences & Engineering, King Abdullah University of Science and Technology, Thuwal, 23955–6900, Kingdom of Saudi Arabia
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, 23955–6900, Kingdom of Saudi Arabia
- * E-mail: (MA); (TR)
| | - Timothy Ravasi
- Division of Biological and Environmental Sciences & Engineering, King Abdullah University of Science and Technology, Thuwal, 23955–6900, Kingdom of Saudi Arabia
- KAUST Environmental Epigenetics Program (KEEP), King Abdullah University of Science and Technology, Thuwal, 23955–6900, Kingdom of Saudi Arabia
- * E-mail: (MA); (TR)
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Carradec Q, Götz U, Arnaiz O, Pouch J, Simon M, Meyer E, Marker S. Primary and secondary siRNA synthesis triggered by RNAs from food bacteria in the ciliate Paramecium tetraurelia. Nucleic Acids Res 2015; 43:1818-33. [PMID: 25593325 PMCID: PMC4330347 DOI: 10.1093/nar/gku1331] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In various organisms, an efficient RNAi response can be triggered by feeding cells with bacteria producing double-stranded RNA (dsRNA) against an endogenous gene. However, the detailed mechanisms and natural functions of this pathway are not well understood in most cases. Here, we studied siRNA biogenesis from exogenous RNA and its genetic overlap with endogenous RNAi in the ciliate Paramecium tetraurelia by high-throughput sequencing. Using wild-type and mutant strains deficient for dsRNA feeding we found that high levels of primary siRNAs of both strands are processed from the ingested dsRNA trigger by the Dicer Dcr1, the RNA-dependent RNA polymerases Rdr1 and Rdr2 and other factors. We further show that this induces the synthesis of secondary siRNAs spreading along the entire endogenous mRNA, demonstrating the occurrence of both 3′-to-5′ and 5′-to-3′ transitivity for the first time in the SAR clade of eukaryotes (Stramenopiles, Alveolates, Rhizaria). Secondary siRNAs depend on Rdr2 and show a strong antisense bias; they are produced at much lower levels than primary siRNAs and hardly contribute to RNAi efficiency. We further provide evidence that the Paramecium RNAi machinery also processes single-stranded RNAs from its bacterial food, broadening the possible natural functions of exogenously induced RNAi in this organism.
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Affiliation(s)
- Quentin Carradec
- Institut de Biologie de l'ENS, IBENS, Ecole Normale Supérieure, Inserm, U1024, CNRS, UMR 8197, 75005 Paris, France UPMC, IFD, Sorbonne Universités, 4 place Jussieu, 75252 Paris cedex 05, France
| | - Ulrike Götz
- Zentrum für Human- und Molekularbiologie, Molekulare Zelldynamik, Universität des Saarlandes, Campus A2 4, 66123 Saarbrücken, Germany
| | - Olivier Arnaiz
- Centre de Génétique Moléculaire, CNRS UPR3404, 91198 Gif-sur-Yvette cedex, France
| | - Juliette Pouch
- Institut de Biologie de l'ENS, IBENS, Ecole Normale Supérieure, Inserm, U1024, CNRS, UMR 8197, 75005 Paris, France
| | - Martin Simon
- Zentrum für Human- und Molekularbiologie, Molekulare Zelldynamik, Universität des Saarlandes, Campus A2 4, 66123 Saarbrücken, Germany
| | - Eric Meyer
- Institut de Biologie de l'ENS, IBENS, Ecole Normale Supérieure, Inserm, U1024, CNRS, UMR 8197, 75005 Paris, France
| | - Simone Marker
- Institut de Biologie de l'ENS, IBENS, Ecole Normale Supérieure, Inserm, U1024, CNRS, UMR 8197, 75005 Paris, France Zentrum für Human- und Molekularbiologie, Molekulare Zelldynamik, Universität des Saarlandes, Campus A2 4, 66123 Saarbrücken, Germany
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Ni JZ, Chen E, Gu SG. Complex coding of endogenous siRNA, transcriptional silencing and H3K9 methylation on native targets of germline nuclear RNAi in C. elegans. BMC Genomics 2014; 15:1157. [PMID: 25534009 PMCID: PMC4367959 DOI: 10.1186/1471-2164-15-1157] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 12/10/2014] [Indexed: 11/14/2022] Open
Abstract
Background Small RNA-guided transcriptional silencing (nuclear RNAi) is fundamental to genome integrity and epigenetic inheritance. Despite recent progress in identifying the capability and genetic requirements for nuclear RNAi in Caenorhabditis elegans, the natural targets and cellular functions of nuclear RNAi remain elusive. Methods To resolve this gap, we coordinately examined the genome-wide profiles of transcription, histone H3 lysine 9 methylation (H3K9me) and endogenous siRNAs of a germline nuclear Argonaute (hrde-1/wago-9) mutant and identified regions on which transcription activity is markedly increased and/or H3K9me level is markedly decreased relative to wild type animals. Results Our data revealed a distinct set of native targets of germline nuclear RNAi, with the H3K9me response exhibiting both overlapping and non-overlapping distribution with the transcriptional silencing response. Interestingly LTR retrotransposons, but not DNA transposons, are highly enriched in the targets of germline nuclear RNAi. The genomic distribution of the native targets is highly constrained, with >99% of the identified targets present in five autosomes but not in the sex chromosome. By contrast, HRDE-1-associated small RNAs correspond to all chromosomes. In addition, we found that the piRNA pathway is not required for germline nuclear RNAi activity on native targets. Conclusion Germline nuclear RNAi in C. elegans is required to silence retrotransposons but not DNA transposon. Transcriptional silencing and H3K9me can occur independently of each other on the native targets of nuclear RNAi in C. elegans. Our results rule out a simple model in which nuclear Argonaute protein-associated-small RNAs are sufficient to trigger germline nuclear RNAi responses. In addition, the piRNA pathway and germline nuclear RNAi are specialized to target different types of foreign genetic elements for genome surveillance in C. elegans. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1157) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | - Sam Guoping Gu
- Department of Molecular Biology and Biochemistry, Rutgers the State University of New Jersey, Nelson Labs A125, 604 Allison Road, Piscataway, NJ 08854, USA.
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Youngman EM, Claycomb JM. From early lessons to new frontiers: the worm as a treasure trove of small RNA biology. Front Genet 2014; 5:416. [PMID: 25505902 PMCID: PMC4245922 DOI: 10.3389/fgene.2014.00416] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Accepted: 11/07/2014] [Indexed: 02/02/2023] Open
Abstract
In the past 20 years, the tiny soil nematode Caenorhabditis elegans has provided critical insights into our understanding of the breadth of small RNA-mediated gene regulatory activities. The first microRNA was identified in C. elegans in 1993, and the understanding that dsRNA was the driving force behind RNA-mediated gene silencing came from experiments performed in C. elegans in 1998. Likewise, early genetic screens in C. elegans for factors involved in RNA interference pointed to conserved mechanisms for small RNA-mediated gene silencing pathways, placing the worm squarely among the founding fathers of a now extensive field of molecular biology. Today, the worm continues to be at the forefront of ground-breaking insight into small RNA-mediated biology. Recent studies have revealed with increasing mechanistic clarity that C. elegans possesses an extensive nuclear small RNA regulatory network that encompasses not only gene silencing but also gene activating roles. Further, a portrait is emerging whereby small RNA pathways play key roles in integrating responses to environmental stimuli and transmitting epigenetic information about such responses from one generation to the next. Here we discuss endogenous small RNA pathways in C. elegans and the insight worm biology has provided into the mechanisms employed by these pathways. We touch on the increasingly spectacular diversity of small RNA biogenesis and function, and discuss the relevance of lessons learned in the worm for human biology.
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Affiliation(s)
| | - Julie M Claycomb
- Department of Molecular Genetics, University of Toronto Toronto, ON, Canada
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Global effects of the CSR-1 RNA interference pathway on the transcriptional landscape. Nat Struct Mol Biol 2014; 21:358-65. [PMID: 24681887 PMCID: PMC4068146 DOI: 10.1038/nsmb.2801] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 03/02/2014] [Indexed: 12/20/2022]
Abstract
Argonaute proteins and their small RNA cofactors short interfering RNAs are known to inhibit gene expression at the transcriptional and post-transcriptional levels. In Caenorhabditis elegans, the Argonaute CSR-1 binds thousands of endogenous siRNAs (endo-siRNAs) that are antisense to germline transcripts. However, its role in gene expression regulation remains controversial. Here we used genome-wide profiling of nascent RNA transcripts and found that the CSR-1 RNA interference pathway promoted sense-oriented RNA polymerase II transcription. Moreover, a loss of CSR-1 function resulted in global increase in antisense transcription and ectopic transcription of silent chromatin domains, which led to reduced chromatin incorporation of centromere-specific histone H3. On the basis of these findings, we propose that the CSR-1 pathway helps maintain the directionality of active transcription, thereby propagating the distinction between transcriptionally active and silent genomic regions.
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Shirayama M, Stanney W, Gu W, Seth M, Mello CC. The Vasa Homolog RDE-12 engages target mRNA and multiple argonaute proteins to promote RNAi in C. elegans. Curr Biol 2014; 24:845-51. [PMID: 24684931 DOI: 10.1016/j.cub.2014.03.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 02/27/2014] [Accepted: 03/04/2014] [Indexed: 12/12/2022]
Abstract
Argonaute (AGO) proteins are key nuclease effectors of RNAi. Although purified AGOs can mediate a single round of target RNA cleavage in vitro, accessory factors are required for small interfering RNA (siRNA) loading and to achieve multiple-target turnover. To identify AGO cofactors, we immunoprecipitated the C. elegans AGO WAGO-1, which engages amplified small RNAs during RNAi. These studies identified a robust association between WAGO-1 and a conserved Vasa ATPase-related protein RDE-12. rde-12 mutants are deficient in RNAi, including viral suppression, and fail to produce amplified secondary siRNAs and certain endogenous siRNAs (endo-siRNAs). RDE-12 colocalizes with WAGO-1 in germline P granules and in cytoplasmic and perinuclear foci in somatic cells. These findings and our genetic studies suggest that RDE-12 is first recruited to target mRNA by upstream AGOs (RDE-1 and ERGO-1), where it promotes small RNA amplification and/or WAGO-1 loading. Downstream of these events, RDE-12 forms an RNase-resistant (target mRNA-independent) complex with WAGO-1 and may thus have additional functions in target mRNA surveillance and silencing.
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Affiliation(s)
- Masaki Shirayama
- Program in Molecular Medicine, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA; RNA Therapeutics Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA; Howard Hughes Medical Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA
| | - William Stanney
- Program in Molecular Medicine, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA; RNA Therapeutics Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA
| | - Weifeng Gu
- Program in Molecular Medicine, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA; RNA Therapeutics Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA
| | - Meetu Seth
- Program in Molecular Medicine, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA; RNA Therapeutics Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA; Howard Hughes Medical Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA
| | - Craig C Mello
- Program in Molecular Medicine, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA; RNA Therapeutics Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA; Howard Hughes Medical Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA.
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Identification of microRNAs in the coral Stylophora pistillata. PLoS One 2014; 9:e91101. [PMID: 24658574 PMCID: PMC3962355 DOI: 10.1371/journal.pone.0091101] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 02/06/2014] [Indexed: 12/22/2022] Open
Abstract
Coral reefs are major contributors to marine biodiversity. However, they are in rapid decline due to global environmental changes such as rising sea surface temperatures, ocean acidification, and pollution. Genomic and transcriptomic analyses have broadened our understanding of coral biology, but a study of the microRNA (miRNA) repertoire of corals is missing. miRNAs constitute a class of small non-coding RNAs of ∼22 nt in size that play crucial roles in development, metabolism, and stress response in plants and animals alike. In this study, we examined the coral Stylophora pistillata for the presence of miRNAs and the corresponding core protein machinery required for their processing and function. Based on small RNA sequencing, we present evidence for 31 bona fide microRNAs, 5 of which (miR-100, miR-2022, miR-2023, miR-2030, and miR-2036) are conserved in other metazoans. Homologues of Argonaute, Piwi, Dicer, Drosha, Pasha, and HEN1 were identified in the transcriptome of S. pistillata based on strong sequence conservation with known RNAi proteins, with additional support derived from phylogenetic trees. Examination of putative miRNA gene targets indicates potential roles in development, metabolism, immunity, and biomineralisation for several of the microRNAs. Here, we present first evidence of a functional RNAi machinery and five conserved miRNAs in S. pistillata, implying that miRNAs play a role in organismal biology of scleractinian corals. Analysis of predicted miRNA target genes in S. pistillata suggests potential roles of miRNAs in symbiosis and coral calcification. Given the importance of miRNAs in regulating gene expression in other metazoans, further expression analyses of small non-coding RNAs in transcriptional studies of corals should be informative about miRNA-affected processes and pathways.
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Hoogstrate SW, Volkers RJ, Sterken MG, Kammenga JE, Snoek LB. Nematode endogenous small RNA pathways. WORM 2014; 3:e28234. [PMID: 25340013 PMCID: PMC4205135 DOI: 10.4161/worm.28234] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 02/05/2014] [Accepted: 02/14/2014] [Indexed: 01/25/2023]
Abstract
The discovery of small RNA silencing pathways has greatly extended our knowledge of gene regulation. Small RNAs have been presumed to play a role in every field of biology because they affect many biological processes via regulation of gene expression and chromatin remodeling. Most well-known examples of affected processes are development, fertility, and maintenance of genome stability. Here we review the role of the three main endogenous small RNA silencing pathways in Caenorhabditis elegans: microRNAs, endogenous small interfering RNAs, and PIWI-interacting RNAs. After providing an entry-level overview on how these pathways function, we discuss research on other nematode species providing insight into the evolution of these small RNA pathways. In understanding the differences between the endogenous small RNA pathways and their evolution, a more comprehensive picture is formed of the functions and effects of small RNAs.
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Affiliation(s)
| | - Rita Jm Volkers
- Laboratory of Nematology; Wageningen University; Wageningen, The Netherlands
| | - Mark G Sterken
- Laboratory of Nematology; Wageningen University; Wageningen, The Netherlands
| | - Jan E Kammenga
- Laboratory of Nematology; Wageningen University; Wageningen, The Netherlands
| | - L Basten Snoek
- Laboratory of Nematology; Wageningen University; Wageningen, The Netherlands
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Marker genes for activation of the RNA interference (RNAi) pathway in the free-living nematode Caenorhabditis elegans and RNAi development in the ovine nematode Teladorsagia circumcincta. J Helminthol 2013; 89:208-16. [PMID: 24345514 DOI: 10.1017/s0022149x13000801] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The nematode Teladorsagia circumcincta is a major cause of parasitic gastroenteritis in sheep in temperate regions. The development of resistance to the major anthelmintic classes used for its control is a threat to small ruminant farming sustainability. Vaccination is a potential alternative control method for this nematode. Gene datasets can be exploited to identify potential vaccine candidates and these validated further by methods such as RNA interference (RNAi) prior to vaccine trials. Previous reports indicate that RNAi in parasitic nematodes is inconsistent and, to date, there are no internal controls that indicate activation of the RNAi pathway in response to double-stranded RNA (dsRNA). The present aims were to determine whether or not the transcription levels of potential marker genes in the RNAi pathway could indicate activation of the pathway in Caenorhabditis elegans and to develop an RNAi platform in T. circumcincta. In C. elegans, transcript levels of three candidate marker genes, Ce-dcr-1 (Dicer), Ce-ego-1 (Enhancer of Glp-One family member) and Ce-rsd-3 (RNAi Spreading Defective), were analysed and results indicated that activation of the pathway had no effect on transcript levels of these genes. In T. circumcincta, two vaccine candidate genes from the Activation-associated Secreted Protein (ASP) family were targets for knockdown. RNAi experiments showed successful silencing of both targets, although inconsistencies in efficacy were observed. After testing a number of parameters that might affect variability, it was found that the length of the storage period of the larvae plays an important role in the consistency of the RNAi results.
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Rechavi O. Guest list or black list: heritable small RNAs as immunogenic memories. Trends Cell Biol 2013; 24:212-20. [PMID: 24231398 DOI: 10.1016/j.tcb.2013.10.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 10/10/2013] [Accepted: 10/11/2013] [Indexed: 11/24/2022]
Abstract
Small RNA-mediated gene silencing plays a pivotal role in genome immunity by recognizing and eliminating viruses and transposons that may otherwise colonize the genome. However, individual genomic parasites are highly diverse and employ multiple immune-evasion techniques, making this silencing challenging. Here I review a new theory proposing that the integrity of the germline is maintained by transgenerationally transmitted RNA 'memories' that record ancestral gene expression patterns and delineate 'self' from 'foreign' sequences. To maintain such recollection, two tactics are employed in parallel: 'black listing' of invading nucleic acids and 'guest listing' of endogenous genes. Studies in several organisms have shown that this memorization is used by the next generation of small RNAs to act as 'inherited vaccines' that attack invading elements or as 'inherited licenses' that permit the transcription of autogenous sequences.
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Affiliation(s)
- Oded Rechavi
- Department of Neurobiology, Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel 69978; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel 69978.
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43
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Hall SE, Chirn GW, Lau NC, Sengupta P. RNAi pathways contribute to developmental history-dependent phenotypic plasticity in C. elegans. RNA (NEW YORK, N.Y.) 2013; 19:306-319. [PMID: 23329696 PMCID: PMC3677242 DOI: 10.1261/rna.036418.112] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 11/26/2012] [Indexed: 05/30/2023]
Abstract
Early environmental experiences profoundly influence adult phenotypes through complex mechanisms that are poorly understood. We previously showed that adult Caenorhabditis elegans that transiently passed through the stress-induced dauer larval stage (post-dauer adults) exhibit significant changes in gene expression profiles, chromatin states, and life history traits when compared with adults that bypassed the dauer stage (control adults). These wild-type, isogenic animals of equivalent developmental stages exhibit different signatures of molecular marks that reflect their distinct developmental trajectories. To gain insight into the mechanisms that contribute to these developmental history-dependent phenotypes, we profiled small RNAs from post-dauer and control adults by deep sequencing. RNA interference (RNAi) pathways are known to regulate genome-wide gene expression both at the chromatin and post-transcriptional level. By quantifying changes in endogenous small interfering RNA (endo-siRNA) levels in post-dauer as compared with control animals, our analyses identified a subset of genes that are likely targets of developmental history-dependent reprogramming through a complex RNAi-mediated mechanism. Mutations in specific endo-siRNA pathways affect expected gene expression and chromatin state changes for a subset of genes in post-dauer animals, as well as disrupt their increased brood size phenotype. We also find that both chromatin state and endo-siRNA distribution in dauers are unique, and suggest that remodeling in dauers provides a template for the subsequent establishment of adult post-dauer profiles. Our results indicate a role for endo-siRNA pathways as a contributing mechanism to early experience-dependent phenotypic plasticity in adults, and describe how developmental history can program adult physiology and behavior via epigenetic mechanisms.
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Affiliation(s)
- Sarah E. Hall
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Gung-Wei Chirn
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Nelson C. Lau
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Piali Sengupta
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts 02454, USA
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Zhang H, Ehrenkaufer GM, Hall N, Singh U. Small RNA pyrosequencing in the protozoan parasite Entamoeba histolytica reveals strain-specific small RNAs that target virulence genes. BMC Genomics 2013; 14:53. [PMID: 23347563 PMCID: PMC3610107 DOI: 10.1186/1471-2164-14-53] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Accepted: 01/02/2013] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Small RNA mediated gene silencing is a well-conserved regulatory pathway. In the parasite Entamoeba histolytica an endogenous RNAi pathway exists, however, the depth and diversity of the small RNA population remains unknown. RESULTS To characterize the small RNA population that associates with E. histolytica Argonaute-2 (EhAGO2-2), we immunoprecipitated small RNAs that associate with it and performed one full pyrosequencing run. Data analysis revealed new features of the 27nt small RNAs including the 5'-G predominance, distinct small RNA distribution patterns on protein coding genes, small RNAs mapping to both introns and exon-exon junctions, and small RNA targeted genes that are clustered particularly in sections of genome duplication. Characterization of genomic loci to which both sense and antisense small RNAs mapped showed that both sets of small RNAs have 5'-polyphosphate termini; strand-specific RT-PCR detected transcripts in both directions at these loci suggesting that both transcripts may serve as template for small RNA generation. In order to determine whether small RNA abundance patterns account for strain-specific gene expression profiles of E. histolytica virulent and non-virulent strains, we sequenced small RNAs from a non-virulent strain and found that small RNAs mapped to genes in a manner consistent with their regulation of strain-specific virulence genes. CONCLUSIONS We provided a full spectrum analysis for E. histolytica AGO2-2 associated 27nt small RNAs. Additionally, comparative analysis of small RNA populations from virulent and non-virulent amebic strains indicates that small RNA populations may regulate virulence genes.
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Affiliation(s)
- Hanbang Zhang
- Division of Infectious Diseases, Department of Internal Medicine, Stanford University School of Medicine, Stanford, California 94305-5107, USA
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Protection from feed-forward amplification in an amplified RNAi mechanism. Cell 2013; 151:885-899. [PMID: 23141544 DOI: 10.1016/j.cell.2012.10.022] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 07/02/2012] [Accepted: 10/04/2012] [Indexed: 11/21/2022]
Abstract
The effectiveness of RNA interference (RNAi) in many organisms is potentiated through the signal-amplifying activity of a targeted RNA-directed RNA polymerase (RdRP) system that can convert a small population of exogenously-encountered dsRNA fragments into an abundant internal pool of small interfering RNA (siRNA). As for any biological amplification system, we expect an underlying architecture that will limit the ability of a randomly encountered trigger to produce an uncontrolled and self-escalating response. Investigating such limits in Caenorhabditis elegans, we find that feed-forward amplification is limited by biosynthetic and structural distinctions at the RNA level between (1) triggers that can produce amplification and (2) siRNA products of the amplification reaction. By assuring that initial (primary) siRNAs can act as triggers but not templates for activation, and that the resulting (secondary) siRNAs can enforce gene silencing on additional targets without unbridled trigger amplification, the system achieves substantial but fundamentally limited signal amplification.
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47
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Gu S, Jin L, Zhang Y, Huang Y, Zhang F, Valdmanis PN, Kay MA. The loop position of shRNAs and pre-miRNAs is critical for the accuracy of dicer processing in vivo. Cell 2013; 151:900-911. [PMID: 23141545 DOI: 10.1016/j.cell.2012.09.042] [Citation(s) in RCA: 225] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/20/2012] [Accepted: 09/27/2012] [Indexed: 01/02/2023]
Abstract
Short hairpin RNA (shRNA)-induced RNAi is used for biological discovery and therapeutics. Dicer, whose normal role is to liberate endogenous miRNAs from their precursors, processes shRNAs into different biologically active siRNAs, affecting their efficacy and potential for off-targeting. We found that, in cells, Dicer induced imprecise cleavage events around the expected sites based on the previously described 5'/3' counting rules. These promiscuous noncanonical cleavages were abrogated when the cleavage site was positioned 2 nt from a bulge or loop. Interestingly, we observed that the ~1/3 of mammalian endogenous pre-miRNAs that contained such structures were more precisely processed by Dicer. Implementing a "loop-counting rule," we designed potent anti-HCV shRNAs with substantially reduced off-target effects. Our results suggest that Dicer recognizes the loop/bulge structure in addition to the ends of shRNAs/pre-miRNAs for accurate processing. This has important implications for both miRNA processing and future design of shRNAs for RNAi-based genetic screens and therapies.
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Affiliation(s)
- Shuo Gu
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Lan Jin
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Yue Zhang
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Yong Huang
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Feijie Zhang
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Paul N Valdmanis
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Mark A Kay
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA.
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48
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Abstract
The significance of noncoding RNAs in animal biology is being increasingly recognized. The nematode Caenorhabditis elegans has an extensive system of short RNAs that includes microRNAs, piRNAs, and endogenous siRNAs, which regulate development, control life span, provide resistance to viruses and transposons, and monitor gene duplications. Progress in our understanding of short RNAs was stimulated by the discovery of RNA interference, a phenomenon of sequence-specific gene silencing induced by exogenous double-stranded RNA, at the turn of the twenty-first century. This chapter provides a broad overview of the exogenous and endogenous RNAi processes in C. elegans and describes recent advances in genetic, genomic, and molecular analyses of nematode's short RNAs and proteins involved in the RNAi-related pathways.
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Affiliation(s)
- Alla Grishok
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York, USA.
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49
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Garcia D, Garcia S, Pontier D, Marchais A, Renou JP, Lagrange T, Voinnet O. Ago hook and RNA helicase motifs underpin dual roles for SDE3 in antiviral defense and silencing of nonconserved intergenic regions. Mol Cell 2012; 48:109-20. [PMID: 22940249 DOI: 10.1016/j.molcel.2012.07.028] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 05/22/2012] [Accepted: 07/25/2012] [Indexed: 10/27/2022]
Abstract
In Arabidopsis thaliana, the putative RNA-helicase SDE3 assists posttranscriptional-gene-silencing (PTGS) amplification by RNA-dependent-RNA-polymerase-6 (RDR6). SDE3 homologs in Drosophila, worm and human contribute to silence viruses, transposons or recently duplicated genes but the underlying mechanisms remain largely unknown. Here, we demonstrate that SDE3 is present with the PTGS effectors AGO1 and AGO2 in higher-order protein complexes owing to a specialized GW-repeat-containing C-terminal domain. We uncover an essential contribution of the RNA-helicase activity and a facilitating role for AGO binding in SDE3 action, which occurs downstream of RDR6. We show that these biochemical properties underpin dual roles for SDE3 in antiviral defense and, unexpectedly, in transposon silencing via a hitherto unanticipated pathway that correlates with DNA methylation, suggesting a continuum of action between PTGS and chromatin-level silencing. We identified endogenous SDE3 targets corresponding to nonconserved intergenic regions, transposons and recently evolved pseudogenes, unraveling striking functional convergences among plant and metazoan SDE3 pathways.
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Affiliation(s)
- Damien Garcia
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Strasbourg, France
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50
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Biogenesis and mechanism of action of small non-coding RNAs: insights from the point of view of structural biology. Int J Mol Sci 2012; 13:10268-10295. [PMID: 22949860 PMCID: PMC3431858 DOI: 10.3390/ijms130810268] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 07/17/2012] [Accepted: 08/02/2012] [Indexed: 01/17/2023] Open
Abstract
Non-coding RNAs are dominant in the genomic output of the higher organisms being not simply occasional transcripts with idiosyncratic functions, but constituting an extensive regulatory network. Among all the species of non-coding RNAs, small non-coding RNAs (miRNAs, siRNAs and piRNAs) have been shown to be in the core of the regulatory machinery of all the genomic output in eukaryotic cells. Small non-coding RNAs are produced by several pathways containing specialized enzymes that process RNA transcripts. The mechanism of action of these molecules is also ensured by a group of effector proteins that are commonly engaged within high molecular weight protein-RNA complexes. In the last decade, the contribution of structural biology has been essential to the dissection of the molecular mechanisms involved in the biosynthesis and function of small non-coding RNAs.
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