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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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Sen T, McCormick C, Rogers AK. Small RNA-mediated genetic switches coordinate ALG-3/4 small RNA pathway function. Nucleic Acids Res 2024:gkae586. [PMID: 38967024 DOI: 10.1093/nar/gkae586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 06/20/2024] [Accepted: 06/25/2024] [Indexed: 07/06/2024] Open
Abstract
Coordination of gene regulatory networks is necessary for proper execution of cellular programs throughout development. RNA interference (RNAi) is an essential regulatory mechanism in all metazoans. Proper RNAi-mediated gene regulation requires coordination of several RNAi branches to ensure homeostasis. For example, in Caenorhabditis elegans, the Argonautes, ALG-3 and ALG-4, are expressed specifically during spermatogenesis (L4 stage) and bind small interfering RNAs (siRNAs) complementary to sperm-enriched genes. We find that alg-3 and alg-4 are regulated by siRNAs. Our work shows that gene switches are operated via these siRNAs to regulate the Argonautes' expression in a temporal manner. This RNAi-to-RNAi regulatory cascade is essential for coordinating ALG-3/4 pathway function, particularly during heat stress, to provide thermotolerant sperm-based fertility. This work provides insight into one regulatory motif used to maintain RNAi homeostasis, across developmental stages, despite environmental stressors. As RNAi pathways are evolutionarily conserved, other species likely use similar regulatory architectures to maintain RNAi homeostasis.
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Affiliation(s)
- Trilotma Sen
- Department of Biology, University of Texas at Arlington, Arlington, TX 76019, USA
| | - Cara McCormick
- Department of Biology, University of Texas at Arlington, Arlington, TX 76019, USA
| | - Alicia K Rogers
- Department of Biology, University of Texas at Arlington, Arlington, TX 76019, USA
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Gajjar G, Huggins HP, Kim ES, Huang W, Bonnet FX, Updike DL, Keiper BD. Two germ granule eIF4E isoforms reside in different mRNPs to hand off C elegans mRNAs from translational repression to activation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.24.595216. [PMID: 38826235 PMCID: PMC11142241 DOI: 10.1101/2024.05.24.595216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
We studied the function of translation factor eIF4E isoforms in regulating mRNAs in germ cell granules/condensates. Translational control of mRNAs plays an essential role in germ cell gene regulation. Messenger ribonucleoprotein (mRNP) complexes assemble on mRNAs as they move from the nucleus into perinuclear germ granules to exert both positive and negative post-transcriptional regulation in the cytoplasm. In C. elegans , germ granules are surprisingly dynamic mRNP condensates that remodel during development. Two eIF4E isoforms (called IFE-1 and IFE-3), eIF4E-Interacting Proteins (4EIPs), RBPs, DEAD-box helicases, polyadenylated mRNAs, Argonautes and miRNAs all occupy positions in germ granules. Affinity purification of IFE-1 and IFE-3 allowed mass spectrometry and mRNA-Seq to identify the proteins and mRNAs that populate stable eIF4E mRNPs. We find translationally controlled mRNAs (e.g. pos-1, mex-3, spn-4, etc.) enriched in IFE-3 mRNPs, but excluded from IFE-1 mRNPs. These mRNAs also require IFE-1 for efficient translation. The findings support a model in which oocytes and embryos utilize the two eIF4Es for opposite purposes on critically regulated germline mRNAs. Careful colocalization of the eIF4Es with other germ granule components suggests an architecture in which GLH-1, PGL-1 and the IFEs are stratified to facilitate sequential interactions for mRNAs. Biochemical characterization demonstrates opposing yet cooperative roles for IFE-3 and IFE-1 to hand-off of translationally controlled mRNAs from the repressed to the activated state, respectively. The model involves eIF4E mRNPs shuttling mRNAs through nuclear pore-associated granules/condensates to cytoplasmic ribosomes.
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Danlasky BM, Martinez M, Cassani M, Bodas D, Putnam A, Seydoux G. The P granule antibody KT3 recognizes epitopes in both PGL-1 and PGL-3. MICROPUBLICATION BIOLOGY 2024; 2024:10.17912/micropub.biology.001137. [PMID: 38440332 PMCID: PMC10910292 DOI: 10.17912/micropub.biology.001137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 02/09/2024] [Accepted: 02/13/2024] [Indexed: 03/06/2024]
Abstract
The KT3 antibody is a commercially available antibody that recognizes the P granule protein PGL-3 (Takeda et al., 2008). Using immunostaining and western blotting of purified peptide fragments, we show that KT3 recognizes both PGL-3 and its paralog PGL-1 , likely through a shared epitope in the intrinsically disordered region.
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Affiliation(s)
- Brennan M Danlasky
- Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine
| | - Mario Martinez
- Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine
| | - Madeline Cassani
- Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine
| | - Devavrat Bodas
- Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine
| | - Andrea Putnam
- Molecular Biology and Genetics, University of Wisconsin–Madison, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine
| | - Geraldine Seydoux
- Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine
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5
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Schwartz AZA, Abdu Y, Nance J. ZIF-1-mediated degradation of zinc finger proteins in the Caenorhabditis elegans germ line. Genetics 2023; 225:iyad160. [PMID: 37647858 PMCID: PMC10627257 DOI: 10.1093/genetics/iyad160] [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: 07/07/2023] [Revised: 08/21/2023] [Accepted: 08/21/2023] [Indexed: 09/01/2023] Open
Abstract
Rapid and conditional protein depletion is the gold standard genetic tool for deciphering the molecular basis of developmental processes. Previously, we showed that by conditionally expressing the E3 ligase substrate adaptor ZIF-1 in Caenorhabditis elegans somatic cells, proteins tagged with the first CCCH Zn finger 1 (ZF1) domain from the germline regulator PIE-1 degrade rapidly, resulting in loss-of-function phenotypes. The described role of ZIF-1 is to clear PIE-1 and several other CCCH Zn finger proteins from early somatic cells, helping to enrich them in germline precursor cells. Here, we show that proteins tagged with the PIE-1 ZF1 domain are subsequently cleared from primordial germ cells (PGCs) in embryos and from undifferentiated germ cells in larvae and adults by ZIF-1. We harness germline ZIF-1 activity to degrade a ZF1-tagged fusion protein from PGCs and show that its depletion produces phenotypes equivalent to those of a null mutation. Our findings reveal that ZIF-1 transitions from degrading CCCH Zn finger proteins in somatic cells to clearing them from undifferentiated germ cells, and that ZIF-1 activity can be harnessed as a new genetic tool to study the early germline.
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Affiliation(s)
- Aaron Z A Schwartz
- Department of Cell Biology, NYU Grossman School of Medicine, New York, NY 10016, USA
- Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, NY 10016, USA
| | - Yusuff Abdu
- Department of Cell Biology, NYU Grossman School of Medicine, New York, NY 10016, USA
- Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, NY 10016, USA
| | - Jeremy Nance
- Department of Cell Biology, NYU Grossman School of Medicine, New York, NY 10016, USA
- Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, NY 10016, USA
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6
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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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7
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Schwartz AZ, Abdu Y, Nance J. ZIF-1-mediated degradation of endogenous and heterologous zinc finger proteins in the C. elegans germ line. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.10.548405. [PMID: 37502839 PMCID: PMC10369855 DOI: 10.1101/2023.07.10.548405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Rapid and conditional protein depletion is the gold standard genetic tool for deciphering the molecular basis of developmental processes. Previously, we showed that by conditionally expressing the E3 ligase substrate adaptor ZIF-1 in Caenorhabditis elegans somatic cells, proteins tagged with the first CCCH Zn finger (ZF1) domain from the germline regulator PIE-1 degrade rapidly, resulting in loss-of-function phenotypes. The described role of ZIF-1 is to clear PIE-1 and several other CCCH Zn finger proteins from early somatic cells, helping to enrich them in germline precursor cells. Here, we show that proteins tagged with the PIE-1 ZF1 domain are subsequently cleared from primordial germ cells in embryos and from undifferentiated germ cells in larvae and adults by ZIF-1. We harness germline ZIF-1 activity to degrade a ZF1-tagged heterologous protein from PGCs and show that its depletion produces phenotypes equivalent to those of a null mutation. Our findings reveal that ZIF-1 switches roles from degrading CCCH Zn finger proteins in somatic cells to clearing them from undifferentiated germ cells, and that ZIF-1 activity can be harnessed as a new genetic tool to study the early germ line.
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Affiliation(s)
- Aaron Z.A. Schwartz
- Department of Cell Biology, NYU Grossman School of Medicine, New York NY 10016
- Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York NY 10016
| | - Yusuff Abdu
- Department of Cell Biology, NYU Grossman School of Medicine, New York NY 10016
- Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York NY 10016
| | - Jeremy Nance
- Department of Cell Biology, NYU Grossman School of Medicine, New York NY 10016
- Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York NY 10016
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Albarqi MMY, Ryder SP. The role of RNA-binding proteins in orchestrating germline development in Caenorhabditis elegans. Front Cell Dev Biol 2023; 10:1094295. [PMID: 36684428 PMCID: PMC9846511 DOI: 10.3389/fcell.2022.1094295] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 12/19/2022] [Indexed: 01/06/2023] Open
Abstract
RNA passed from parents to progeny controls several aspects of early development. The germline of the free-living nematode Caenorhabditis elegans contains many families of evolutionarily conserved RNA-binding proteins (RBPs) that target the untranslated regions of mRNA transcripts to regulate their translation and stability. In this review, we summarize what is known about the binding specificity of C. elegans germline RNA-binding proteins and the mechanisms of mRNA regulation that contribute to their function. We examine the emerging role of miRNAs in translational regulation of germline and embryo development. We also provide an overview of current technology that can be used to address the gaps in our understanding of RBP regulation of mRNAs. Finally, we present a hypothetical model wherein multiple 3'UTR-mediated regulatory processes contribute to pattern formation in the germline to ensure the proper and timely localization of germline proteins and thus a functional reproductive system.
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Chiappetta A, Liao J, Tian S, Trcek T. Structural and functional organization of germ plasm condensates. Biochem J 2022; 479:2477-2495. [PMID: 36534469 PMCID: PMC10722471 DOI: 10.1042/bcj20210815] [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: 09/09/2022] [Revised: 11/08/2022] [Accepted: 11/11/2022] [Indexed: 12/23/2022]
Abstract
Reproductive success of metazoans relies on germ cells. These cells develop early during embryogenesis, divide and undergo meiosis in the adult to make sperm and oocytes. Unlike somatic cells, germ cells are immortal and transfer their genetic material to new generations. They are also totipotent, as they differentiate into different somatic cell types. The maintenance of immortality and totipotency of germ cells depends on extensive post-transcriptional and post-translational regulation coupled with epigenetic remodeling, processes that begin with the onset of embryogenesis [1, 2]. At the heart of this regulation lie germ granules, membraneless ribonucleoprotein condensates that are specific to the germline cytoplasm called the germ plasm. They are a hallmark of all germ cells and contain several proteins and RNAs that are conserved across species. Interestingly, germ granules are often structured and tend to change through development. In this review, we describe how the structure of germ granules becomes established and discuss possible functional outcomes these structures have during development.
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Mitrea DM, Mittasch M, Gomes BF, Klein IA, Murcko MA. Modulating biomolecular condensates: a novel approach to drug discovery. Nat Rev Drug Discov 2022; 21:841-862. [PMID: 35974095 PMCID: PMC9380678 DOI: 10.1038/s41573-022-00505-4] [Citation(s) in RCA: 85] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2022] [Indexed: 12/12/2022]
Abstract
In the past decade, membraneless assemblies known as biomolecular condensates have been reported to play key roles in many cellular functions by compartmentalizing specific proteins and nucleic acids in subcellular environments with distinct properties. Furthermore, growing evidence supports the view that biomolecular condensates often form by phase separation, in which a single-phase system demixes into a two-phase system consisting of a condensed phase and a dilute phase of particular biomolecules. Emerging understanding of condensate function in normal and aberrant cellular states, and of the mechanisms of condensate formation, is providing new insights into human disease and revealing novel therapeutic opportunities. In this Perspective, we propose that such insights could enable a previously unexplored drug discovery approach based on identifying condensate-modifying therapeutics (c-mods), and we discuss the strategies, techniques and challenges involved.
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Elaswad MT, Watkins BM, Sharp KG, Munderloh C, Schisa JA. Large RNP granules in Caenorhabditis elegans oocytes have distinct phases of RNA-binding proteins. G3 GENES|GENOMES|GENETICS 2022; 12:6639704. [PMID: 35816006 PMCID: PMC9434171 DOI: 10.1093/g3journal/jkac173] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 06/24/2022] [Indexed: 11/14/2022]
Abstract
The germ line provides an excellent in vivo system to study the regulation and function of RNP granules. Germ granules are conserved germ line-specific RNP granules that are positioned in the Caenorhabditis elegans adult gonad to function in RNA maintenance, regulation, and surveillance. In Caenorhabditis elegans, when oogenesis undergoes extended meiotic arrest, germ granule proteins and other RNA-binding proteins assemble into much larger RNP granules whose hypothesized function is to regulate RNA metabolism and maintain oocyte quality. To gain insight into the function of oocyte RNP granules, in this report, we characterize distinct phases for four protein components of RNP granules in arrested oocytes. We find that the RNA-binding protein PGL-1 is dynamic and has liquid-like properties, while the intrinsically disordered protein MEG-3 has gel-like properties, similar to the properties of the two proteins in small germ granules of embryos. We find that MEX-3 exhibits several gel-like properties but is more dynamic than MEG-3, while CGH-1 is dynamic but does not consistently exhibit liquid-like characteristics and may be an intermediate phase within RNP granules. These distinct phases of RNA-binding proteins correspond to, and may underlie, differential responses to stress. Interestingly, in oocyte RNP granules, MEG-3 is not required for the condensation of PGL-1 or other RNA-binding proteins, which differs from the role of MEG-3 in small, embryonic germ granules. Lastly, we show that the PUF-5 translational repressor appears to promote MEX-3 and MEG-3 condensation into large RNP granules; however, this role may be associated with regulation of oogenesis.
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Affiliation(s)
- Mohamed T Elaswad
- Biochemistry, Cell and Molecular Biology Program, Central Michigan University , Mt. Pleasant, MI 48859, USA
- Department of Biology, Central Michigan University , Mt. Pleasant, MI 48859, USA
| | - Brooklynne M Watkins
- Biochemistry, Cell and Molecular Biology Program, Central Michigan University , Mt. Pleasant, MI 48859, USA
- Department of Biology, Central Michigan University , Mt. Pleasant, MI 48859, USA
| | - Katherine G Sharp
- Department of Biology, Central Michigan University , Mt. Pleasant, MI 48859, USA
| | - Chloe Munderloh
- Department of Biology, Central Michigan University , Mt. Pleasant, MI 48859, USA
| | - Jennifer A Schisa
- Biochemistry, Cell and Molecular Biology Program, Central Michigan University , Mt. Pleasant, MI 48859, USA
- Department of Biology, Central Michigan University , Mt. Pleasant, MI 48859, USA
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12
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Parker DM, Winkenbach LP, Osborne Nishimura E. It’s Just a Phase: Exploring the Relationship Between mRNA, Biomolecular Condensates, and Translational Control. Front Genet 2022; 13:931220. [PMID: 35832192 PMCID: PMC9271857 DOI: 10.3389/fgene.2022.931220] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/07/2022] [Indexed: 11/13/2022] Open
Abstract
Cells spatially organize their molecular components to carry out fundamental biological processes and guide proper development. The spatial organization of RNA within the cell can both promote and result from gene expression regulatory control. Recent studies have demonstrated diverse associations between RNA spatial patterning and translation regulatory control. One form of patterning, compartmentalization in biomolecular condensates, has been of particular interest. Generally, transcripts associated with cytoplasmic biomolecular condensates—such as germ granules, stress granules, and P-bodies—are linked with low translational status. However, recent studies have identified new biomolecular condensates with diverse roles associated with active translation. This review outlines RNA compartmentalization in various condensates that occur in association with repressed or active translational states, highlights recent findings in well-studied condensates, and explores novel condensate behaviors.
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Affiliation(s)
- Dylan M. Parker
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, United States
- Department of Biochemistry, University of Colorado, Boulder, CO, United States
| | - Lindsay P. Winkenbach
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, United States
| | - Erin Osborne Nishimura
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, United States
- *Correspondence: Erin Osborne Nishimura,
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13
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Rodriguez-Crespo D, Nanchen M, Rajopadhye S, Wicky C. The zinc-finger transcription factor LSL-1 is a major regulator of the germline transcriptional program in Caenorhabditis elegans. Genetics 2022; 221:iyac039. [PMID: 35262739 PMCID: PMC9071529 DOI: 10.1093/genetics/iyac039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
Abstract
Specific gene transcriptional programs are required to ensure the proper proliferation and differentiation processes underlying the production of specialized cells during development. Gene activity is mainly regulated by the concerted action of transcription factors and chromatin proteins. In the nematode Caenorhabditis elegans, mechanisms that silence improper transcriptional programs in germline and somatic cells have been well studied, however, how are tissue-specific sets of genes turned on is less known. LSL-1 is herein defined as a novel crucial transcriptional regulator of germline genes in C. elegans. LSL-1 is first detected in the P4 blastomere and remains present at all stages of germline development, from primordial germ cell proliferation to the end of meiotic prophase. lsl-1 loss-of-function mutants exhibit many defects including meiotic prophase progression delay, a high level of germline apoptosis, and production of almost no functional gametes. Transcriptomic analysis and ChIP-seq data show that LSL-1 binds to promoters and acts as a transcriptional activator of germline genes involved in various processes, including homologous chromosome pairing, recombination, and genome stability. Furthermore, we show that LSL-1 functions by antagonizing the action of the heterochromatin proteins HPL-2/HP1 and LET-418/Mi2 known to be involved in the repression of germline genes in somatic cells. Based on our results, we propose LSL-1 to be a major regulator of the germline transcriptional program during development.
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Affiliation(s)
| | - Magali Nanchen
- Department of Biology, University of Fribourg, Fribourg 1700, Switzerland
| | - Shweta Rajopadhye
- Department of Biology, University of Fribourg, Fribourg 1700, Switzerland
| | - Chantal Wicky
- Department of Biology, University of Fribourg, Fribourg 1700, Switzerland
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14
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Phillips CM, Updike DL. Germ granules and gene regulation in the Caenorhabditis elegans germline. Genetics 2022; 220:6541922. [PMID: 35239965 PMCID: PMC8893257 DOI: 10.1093/genetics/iyab195] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 10/10/2021] [Indexed: 01/27/2023] Open
Abstract
The transparency of Caenorhabditis elegans provides a unique window to observe and study the function of germ granules. Germ granules are specialized ribonucleoprotein (RNP) assemblies specific to the germline cytoplasm, and they are largely conserved across Metazoa. Within the germline cytoplasm, they are positioned to regulate mRNA abundance, translation, small RNA production, and cytoplasmic inheritance to help specify and maintain germline identity across generations. Here we provide an overview of germ granules and focus on the significance of more recent observations that describe how they further demix into sub-granules, each with unique compositions and functions.
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Affiliation(s)
- Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA,Corresponding author: (C.M.P.); (D.L.U.)
| | - Dustin L Updike
- The Mount Desert Island Biological Laboratory, Bar Harbor, ME 04672, USA,Corresponding author: (C.M.P.); (D.L.U.)
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15
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Membrane-associated cytoplasmic granules carrying the Argonaute protein WAGO-3 enable paternal epigenetic inheritance in Caenorhabditis elegans. Nat Cell Biol 2022; 24:217-229. [PMID: 35132225 PMCID: PMC9973253 DOI: 10.1038/s41556-021-00827-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 12/03/2021] [Indexed: 01/04/2023]
Abstract
Epigenetic inheritance describes the transmission of gene regulatory information across generations without altering DNA sequences, enabling offspring to adapt to environmental conditions. Small RNAs have been implicated in this, through both the oocyte and the sperm. However, as much of the cellular content is extruded during spermatogenesis, it is unclear whether cytoplasmic small RNAs can contribute to epigenetic inheritance through sperm. Here we identify a sperm-specific germ granule, termed the paternal epigenetic inheritance (PEI) granule, that mediates paternal epigenetic inheritance by retaining the cytoplasmic Argonaute protein WAGO-3 during spermatogenesis in Caenorhabditis elegans. We identify the PEI granule proteins PEI-1 and PEI-2, which have distinct functions in this process: granule formation, Argonaute selectivity and subcellular localization. We show that PEI granule segregation is coupled to the transport of sperm-specific secretory vesicles through PEI-2 in an S-palmitoylation-dependent manner. PEI-like proteins are found in humans, suggesting that the identified mechanism may be conserved.
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16
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SATO K. Multiple roles of endocytosis and autophagy in intracellular remodeling during oocyte-to-embryo transition. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2022; 98:207-221. [PMID: 35545527 PMCID: PMC9130481 DOI: 10.2183/pjab.98.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 02/15/2022] [Indexed: 06/15/2023]
Abstract
Fertilization is the starting point for creating new progeny. At this time, the highly differentiated oocyte and sperm fuse to form one zygote, which is then converted into a pluripotent early embryo. Recent studies have shown that the lysosomal degradation system via autophagy and endocytosis plays important roles in the remodeling of intracellular components during oocyte-to-embryo transition. For example, in Caenorhabditis elegans, zygotes show high endocytic activity, and some populations of maternal membrane proteins are selectively internalized and delivered to lysosomes for degradation. Furthermore, fertilization triggers selective autophagy of sperm-derived paternal mitochondria, which establishes maternal inheritance of mitochondrial DNA. In addition, it has been shown that autophagy via liquid-liquid phase separation results in the selective degradation of some germ granule components, which are distributed to somatic cells of early embryos. This review outlines the physiological functions of the lysosomal degradation system and its molecular mechanisms in C. elegans and mouse embryos.
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Affiliation(s)
- Ken SATO
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
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17
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Price IF, Hertz HL, Pastore B, Wagner J, Tang W. Proximity labeling identifies LOTUS domain proteins that promote the formation of perinuclear germ granules in C. elegans. eLife 2021; 10:e72276. [PMID: 34730513 PMCID: PMC8616582 DOI: 10.7554/elife.72276] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 11/01/2021] [Indexed: 11/30/2022] Open
Abstract
The germ line produces gametes that transmit genetic and epigenetic information to the next generation. Maintenance of germ cells and development of gametes require germ granules-well-conserved membraneless and RNA-rich organelles. The composition of germ granules is elusive owing to their dynamic nature and their exclusive expression in the germ line. Using Caenorhabditis elegans germ granule, called P granule, as a model system, we employed a proximity-based labeling method in combination with mass spectrometry to comprehensively define its protein components. This set of experiments identified over 200 proteins, many of which contain intrinsically disordered regions (IDRs). An RNA interference-based screen identified factors that are essential for P granule assembly, notably EGGD-1 and EGGD-2, two putative LOTUS-domain proteins. Loss of eggd-1 and eggd-2 results in separation of P granules from the nuclear envelope, germline atrophy, and reduced fertility. We show that IDRs of EGGD-1 are required to anchor EGGD-1 to the nuclear periphery while its LOTUS domains are required to promote the perinuclear localization of P granules. Taken together, our work expands the repertoire of P granule constituents and provides new insights into the role of LOTUS-domain proteins in germ granule organization.
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Affiliation(s)
- Ian F Price
- Department of Biological Chemistry and PharmacologyColumbusUnited States
- Center for RNA BiologyColumbusUnited States
- Ohio State Biochemistry ProgramColumbusUnited States
| | - Hannah L Hertz
- Department of Biological Chemistry and PharmacologyColumbusUnited States
- Center for RNA BiologyColumbusUnited States
| | - Benjamin Pastore
- Department of Biological Chemistry and PharmacologyColumbusUnited States
- Center for RNA BiologyColumbusUnited States
- Ohio State Biochemistry ProgramColumbusUnited States
| | - Jillian Wagner
- Department of Biological Chemistry and PharmacologyColumbusUnited States
- Department of Molecular Genetics, Ohio State UniversityColumbusUnited States
| | - Wen Tang
- Department of Biological Chemistry and PharmacologyColumbusUnited States
- Center for RNA BiologyColumbusUnited States
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18
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Fritsch AW, Diaz-Delgadillo AF, Adame-Arana O, Hoege C, Mittasch M, Kreysing M, Leaver M, Hyman AA, Jülicher F, Weber CA. Local thermodynamics govern formation and dissolution of Caenorhabditis elegans P granule condensates. Proc Natl Acad Sci U S A 2021; 118:e2102772118. [PMID: 34507991 PMCID: PMC8449359 DOI: 10.1073/pnas.2102772118] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2021] [Indexed: 12/31/2022] Open
Abstract
Membraneless compartments, also known as condensates, provide chemically distinct environments and thus spatially organize the cell. A well-studied example of condensates is P granules in the roundworm Caenorhabditis elegans that play an important role in the development of the germline. P granules are RNA-rich protein condensates that share the key properties of liquid droplets such as a spherical shape, the ability to fuse, and fast diffusion of their molecular components. An outstanding question is to what extent phase separation at thermodynamic equilibrium is appropriate to describe the formation of condensates in an active cellular environment. To address this question, we investigate the response of P granule condensates in living cells to temperature changes. We observe that P granules dissolve upon increasing the temperature and recondense upon lowering the temperature in a reversible manner. Strikingly, this temperature response can be captured by in vivo phase diagrams that are well described by a Flory-Huggins model at thermodynamic equilibrium. This finding is surprising due to active processes in a living cell. To address the impact of such active processes on intracellular phase separation, we discuss temperature heterogeneities. We show that, for typical estimates of the density of active processes, temperature represents a well-defined variable and that mesoscopic volume elements are at local thermodynamic equilibrium. Our findings provide strong evidence that P granule assembly and disassembly are governed by phase separation based on local thermal equilibria where the nonequilibrium nature of the cytoplasm is manifested on larger scales.
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Affiliation(s)
- Anatol W Fritsch
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | | | - Omar Adame-Arana
- Division Biological Physics, Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Carsten Hoege
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Matthäus Mittasch
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Dewpoint Therapeutics GmbH, 01307 Dresden, Germany
| | - Moritz Kreysing
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Mark Leaver
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Anthony A Hyman
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Center for Systems Biology Dresden, 01307 Dresden, Germany
- Cluster of Excellence Physics of Life, Technische Universität Dresden, 01307 Dresden, Germany
| | - Frank Jülicher
- Division Biological Physics, Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
- Center for Systems Biology Dresden, 01307 Dresden, Germany
- Cluster of Excellence Physics of Life, Technische Universität Dresden, 01307 Dresden, Germany
| | - Christoph A Weber
- Division Biological Physics, Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany;
- Center for Systems Biology Dresden, 01307 Dresden, Germany
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19
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Cipriani PG, Bay O, Zinno J, Gutwein M, Gan HH, Mayya VK, Chung G, Chen JX, Fahs H, Guan Y, Duchaine TF, Selbach M, Piano F, Gunsalus KC. Novel LOTUS-domain proteins are organizational hubs that recruit C. elegans Vasa to germ granules. eLife 2021; 10:60833. [PMID: 34223818 PMCID: PMC8331183 DOI: 10.7554/elife.60833] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 06/27/2021] [Indexed: 12/16/2022] Open
Abstract
We describe MIP-1 and MIP-2, novel paralogous C. elegans germ granule components that interact with the intrinsically disordered MEG-3 protein. These proteins promote P granule condensation, form granules independently of MEG-3 in the postembryonic germ line, and balance each other in regulating P granule growth and localization. MIP-1 and MIP-2 each contain two LOTUS domains and intrinsically disordered regions and form homo- and heterodimers. They bind and anchor the Vasa homolog GLH-1 within P granules and are jointly required for coalescence of MEG-3, GLH-1, and PGL proteins. Animals lacking MIP-1 and MIP-2 show temperature-sensitive embryonic lethality, sterility, and mortal germ lines. Germline phenotypes include defects in stem cell self-renewal, meiotic progression, and gamete differentiation. We propose that these proteins serve as scaffolds and organizing centers for ribonucleoprotein networks within P granules that help recruit and balance essential RNA processing machinery to regulate key developmental transitions in the germ line.
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Affiliation(s)
- Patricia Giselle Cipriani
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States.,NYU Abu Dhabi Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Olivia Bay
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - John Zinno
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - Michelle Gutwein
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - Hin Hark Gan
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - Vinay K Mayya
- Goodman Cancer Research Centre and Department of Biochemistry, McGill University, Montreal, Canada
| | - George Chung
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - Jia-Xuan Chen
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Hala Fahs
- NYU Abu Dhabi Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Yu Guan
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - Thomas F Duchaine
- Goodman Cancer Research Centre and Department of Biochemistry, McGill University, Montreal, Canada
| | | | - Fabio Piano
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States.,NYU Abu Dhabi Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Kristin C Gunsalus
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States.,NYU Abu Dhabi Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
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20
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Calculli G, Lee HJ, Shen K, Pham U, Herholz M, Trifunovic A, Dillin A, Vilchez D. Systemic regulation of mitochondria by germline proteostasis prevents protein aggregation in the soma of C. elegans. SCIENCE ADVANCES 2021; 7:7/26/eabg3012. [PMID: 34172445 PMCID: PMC8232903 DOI: 10.1126/sciadv.abg3012] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 05/12/2021] [Indexed: 05/15/2023]
Abstract
Protein aggregation causes intracellular changes in neurons, which elicit signals to modulate proteostasis in the periphery. Beyond the nervous system, a fundamental question is whether other organs also communicate their proteostasis status to distal tissues. Here, we examine whether proteostasis of the germ line influences somatic tissues. To this end, we induce aggregation of germline-specific PGL-1 protein in germline stem cells of Caenorhabditis elegans Besides altering the intracellular mitochondrial network of germline cells, PGL-1 aggregation also reduces the mitochondrial content of somatic tissues through long-range Wnt signaling pathway. This process induces the unfolded protein response of the mitochondria in the soma, promoting somatic mitochondrial fragmentation and aggregation of proteins linked with neurodegenerative diseases such as Huntington's and amyotrophic lateral sclerosis. Thus, the proteostasis status of germline stem cells coordinates mitochondrial networks and protein aggregation through the organism.
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Affiliation(s)
- Giuseppe Calculli
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Hyun Ju Lee
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Koning Shen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Uyen Pham
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Marija Herholz
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Aleksandra Trifunovic
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- Institute for Mitochondrial Diseases and Aging, Medical Faculty, University of Cologne, Cologne, Germany
| | - Andrew Dillin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - David Vilchez
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- Faculty of Medicine, University Hospital Cologne, Cologne, Germany
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21
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Evaluating DNA damage response through immunofluorescence staining of primordial germ cells in Caenorhabditis elegans L1 larva. STAR Protoc 2021; 2:100441. [PMID: 33899022 PMCID: PMC8056264 DOI: 10.1016/j.xpro.2021.100441] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
C. elegans L1 larvae have two well-defined primordial germ cells embedded in a niche comprising two somatic gonad precursor cells. Thus, C. elegans provides an ideal model for studying intercellular signaling in response to DNA damage. However, existing staining protocols are focused on worms in later developmental stages and are not optimized for the L1 larvae. Here, we present a revised protocol for assessing the DNA damage response utilizing immunofluorescence staining specifically in C. elegans L1 larva. For complete details on the use and execution of this protocol, please refer to Ou et al. (2019). Primordial germlines in C. elegans L1 larva as ideal stem cell-niche interaction models Evaluating the intercellular DDR within microenvironment by PGC/SGP immunostaining Optimized staining and quantification protocols for C. elegans L1 larva
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22
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Aoki ST, Lynch TR, Crittenden SL, Bingman CA, Wickens M, Kimble J. C. elegans germ granules require both assembly and localized regulators for mRNA repression. Nat Commun 2021; 12:996. [PMID: 33579952 PMCID: PMC7881195 DOI: 10.1038/s41467-021-21278-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 01/14/2021] [Indexed: 02/07/2023] Open
Abstract
Cytoplasmic RNA-protein (RNP) granules have diverse biophysical properties, from liquid to solid, and play enigmatic roles in RNA metabolism. Nematode P granules are paradigmatic liquid droplet granules and central to germ cell development. Here we analyze a key P granule scaffolding protein, PGL-1, to investigate the functional relationship between P granule assembly and function. Using a protein-RNA tethering assay, we find that reporter mRNA expression is repressed when recruited to PGL-1. We determine the crystal structure of the PGL-1 N-terminal region to 1.5 Å, discover its dimerization, and identify key residues at the dimer interface. Mutations of those interface residues prevent P granule assembly in vivo, de-repress PGL-1 tethered mRNA, and reduce fertility. Therefore, PGL-1 dimerization lies at the heart of both P granule assembly and function. Finally, we identify the P granule-associated Argonaute WAGO-1 as crucial for repression of PGL-1 tethered mRNA. We conclude that P granule function requires both assembly and localized regulators.
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Affiliation(s)
- Scott Takeo Aoki
- grid.257413.60000 0001 2287 3919Department of Biochemistry and Molecular Biology, School of Medicine, Indiana University, Indianapolis, IN USA ,grid.14003.360000 0001 2167 3675Department of Biochemistry, University of Wisconsin-Madison, Madison, WI USA
| | - Tina R. Lynch
- grid.14003.360000 0001 2167 3675Department of Biochemistry, University of Wisconsin-Madison, Madison, WI USA
| | - Sarah L. Crittenden
- grid.14003.360000 0001 2167 3675Department of Biochemistry, University of Wisconsin-Madison, Madison, WI USA ,grid.14003.360000 0001 2167 3675Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, WI USA
| | - Craig A. Bingman
- grid.14003.360000 0001 2167 3675Department of Biochemistry, University of Wisconsin-Madison, Madison, WI USA
| | - Marvin Wickens
- grid.14003.360000 0001 2167 3675Department of Biochemistry, University of Wisconsin-Madison, Madison, WI USA
| | - Judith Kimble
- grid.14003.360000 0001 2167 3675Department of Biochemistry, University of Wisconsin-Madison, Madison, WI USA ,grid.14003.360000 0001 2167 3675Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, WI USA
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23
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Mukherjee N, Mukherjee C. Germ cell ribonucleoprotein granules in different clades of life: From insects to mammals. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 12:e1642. [PMID: 33555143 DOI: 10.1002/wrna.1642] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 01/04/2021] [Accepted: 01/05/2021] [Indexed: 12/12/2022]
Abstract
Ribonucleoprotein (RNP) granules are no newcomers in biology. Found in all life forms, ranging across taxa, these membrane-less "organelles" have been classified into different categories based on their composition, structure, behavior, function, and localization. Broadly, they can be listed as stress granules (SGs), processing bodies (PBs), neuronal granules (NGs), and germ cell granules (GCGs). Keeping in line with the topic of this review, RNP granules present in the germ cells have been implicated in a wide range of cellular functions including cellular specification, differentiation, proliferation, and so forth. The mechanisms used by them can be diverse and many of them remain partly obscure and active areas of research. GCGs can be of different types in different organisms and at different stages of development, with multiple types coexisting in the same cell. In this review, the different known subcategories of GCGs have been studied with respect to five distinct model organisms, namely, Drosophila, Caenorhabditis elegans, Xenopus, Zebrafish, and mammals. Of them, the cytoplasmic polar granules in Drosophila, P granules in C. elegans, balbiani body in Xenopus and Zebrafish, and chromatoid bodies in mammals have been specifically emphasized upon. A descriptive account of the same has been provided along with insights into our current understanding of their functional significance with respect to cellular events relating to different developmental and reproductive processes. This article is categorized under: RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Export and Localization > RNA Localization RNA in Disease and Development > RNA in Disease.
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24
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Sundby AE, Molnar RI, Claycomb JM. Connecting the Dots: Linking Caenorhabditis elegans Small RNA Pathways and Germ Granules. Trends Cell Biol 2021; 31:387-401. [PMID: 33526340 DOI: 10.1016/j.tcb.2020.12.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/28/2020] [Accepted: 12/30/2020] [Indexed: 12/15/2022]
Abstract
Germ granules are non-membrane bound, phase-separated organelles, composed of RNAs and proteins. Germ granules are present only within the germ cells of animals, including model systems such as Caenorhabditis elegans, Drosophila, mice, and zebrafish, where they play critical roles in specifying the germ lineage, the inheritance of epigenetic information, and post-transcriptional gene regulation. Across species, conserved germ granule proteins reflect these essential functions. A significant proportion of proteins that localize to germ granules are components of RNA metabolism and small RNA (sRNA) gene regulatory pathways. Here we synthesize our current knowledge of the roles that germ granules and their components play in sRNA pathway functions, transgenerational inheritance, and fertility in the C. elegans germline.
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Affiliation(s)
- Adam E Sundby
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Ruxandra I Molnar
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Julie M Claycomb
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada.
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25
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Lev I, Rechavi O. Germ Granules Allow Transmission of Small RNA-Based Parental Responses in the "Germ Plasm". iScience 2020; 23:101831. [PMID: 33305186 PMCID: PMC7718480 DOI: 10.1016/j.isci.2020.101831] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In the recent decade small RNA-based inheritance has been implicated in a variety of transmitted physiological responses to the environment. In Caenorhabditis elegans, heritable small RNAs rely on RNA-dependent RNA polymerases, RNA-processing machinery, chromatin modifiers, and argonauts for their biogenesis and gene-regulatory effects. Importantly, many of these factors reside in evolutionary conserved germ granules that are required for maintaining germ cell identity and gene expression. Recent literature demonstrated that transient disturbance to the stability of the germ granules leads to changes in the pools of heritable small RNAs and the physiology of the progeny. In this piece, we discuss the heritable consequences of transient destabilization of germ granules and elaborate on the various small RNA-related processes that act in the germ granules. We further propose that germ granules may serve as environment sensors that translate environmental changes to inheritable small RNA-based responses.
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Affiliation(s)
- Itamar Lev
- Department of Neurobiology, Wise Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
- Department of Neurobiology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-BioCenter 1, 1030 Vienna, Austria
| | - Oded Rechavi
- Department of Neurobiology, Wise Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
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26
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Parker DM, Winkenbach LP, Boyson S, Saxton MN, Daidone C, Al-Mazaydeh ZA, Nishimura MT, Mueller F, Osborne Nishimura E. mRNA localization is linked to translation regulation in the Caenorhabditis elegans germ lineage. Development 2020; 147:dev186817. [PMID: 32541012 PMCID: PMC7358130 DOI: 10.1242/dev.186817] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 05/30/2020] [Indexed: 01/01/2023]
Abstract
Caenorhabditis elegans early embryos generate cell-specific transcriptomes despite lacking active transcription, thereby presenting an opportunity to study mechanisms of post-transcriptional regulatory control. We observed that some cell-specific mRNAs accumulate non-homogenously within cells, localizing to membranes, P granules (associated with progenitor germ cells in the P lineage) and P-bodies (associated with RNA processing). The subcellular distribution of transcripts differed in their dependence on 3'UTRs and RNA binding proteins, suggesting diverse regulatory mechanisms. Notably, we found strong but imperfect correlations between low translational status and P granule localization within the progenitor germ lineage. By uncoupling translation from mRNA localization, we untangled a long-standing question: Are mRNAs directed to P granules to be translationally repressed, or do they accumulate there as a consequence of this repression? We found that translational repression preceded P granule localization and could occur independently of it. Further, disruption of translation was sufficient to send homogenously distributed mRNAs to P granules. These results implicate transcriptional repression as a means to deliver essential maternal transcripts to the progenitor germ lineage for later translation.
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Affiliation(s)
- Dylan M Parker
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Lindsay P Winkenbach
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Sam Boyson
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Matthew N Saxton
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Camryn Daidone
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Zainab A Al-Mazaydeh
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
- Department of Biology and Biotechnology, Hashemite University, Zarqa, 13115, Jordan
| | - Marc T Nishimura
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Florian Mueller
- Département Biologie Cellulaire et Infections, Unité Imagerie et Modélisation, Institut Pasteur and CNRS UMR 3691, 28 rue du Docteur Roux, 75015 Paris, France
| | - Erin Osborne Nishimura
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
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27
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Chen W, Hu Y, Lang CF, Brown JS, Schwabach S, Song X, Zhang Y, Munro E, Bennett K, Zhang D, Lee HC. The Dynamics of P Granule Liquid Droplets Are Regulated by the Caenorhabditis elegans Germline RNA Helicase GLH-1 via Its ATP Hydrolysis Cycle. Genetics 2020; 215:421-434. [PMID: 32245789 PMCID: PMC7268986 DOI: 10.1534/genetics.120.303052] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 03/12/2020] [Indexed: 02/06/2023] Open
Abstract
P granules are phase-separated liquid droplets that play important roles in the maintenance of germ cell fate in Caenorhabditis elegans Both the localization and formation of P granules are highly dynamic, but mechanisms that regulate such processes remain poorly understood. Here, we show evidence that the VASA-like germline RNA helicase GLH-1 couples distinct steps of its ATPase hydrolysis cycle to control the formation and disassembly of P granules. In addition, we found that the phenylalanine-glycine-glycine repeats in GLH-1 promote its localization at the perinucleus. Proteomic analyses of the GLH-1 complex with a GLH-1 mutation that interferes with P granule disassembly revealed transient interactions of GLH-1 with several Argonautes and RNA-binding proteins. Finally, we found that defects in recruiting the P granule component PRG-1 to perinuclear foci in the adult germline correlate with the fertility defects observed in various GLH-1 mutants. Together, our results highlight the versatile roles of an RNA helicase in controlling the formation of liquid droplets in space and time.
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Affiliation(s)
- Wenjun Chen
- Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637
| | - Yabing Hu
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China 430074
| | - Charles F Lang
- Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637
| | - Jordan S Brown
- Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637
| | - Sierra Schwabach
- Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637
| | - Xiaoyan Song
- Department of Clinical Laboratory, The Third Affiliated Hospital of Zhengzhou University, China 450052
| | - Ying Zhang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China 430074
| | - Edwin Munro
- Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637
| | - Karen Bennett
- Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65212
| | - Donglei Zhang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China 430074
| | - Heng-Chi Lee
- Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637
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28
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Barucci G, Cornes E, Singh M, Li B, Ugolini M, Samolygo A, Didier C, Dingli F, Loew D, Quarato P, Cecere G. Small-RNA-mediated transgenerational silencing of histone genes impairs fertility in piRNA mutants. Nat Cell Biol 2020; 22:235-245. [PMID: 32015436 PMCID: PMC7272227 DOI: 10.1038/s41556-020-0462-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 01/05/2020] [Indexed: 11/09/2022]
Abstract
PIWI-interacting RNAs (piRNAs) promote fertility in many animals. However, whether this is due to their conserved role in repressing repetitive elements (REs) remains unclear. Here, we show that the progressive loss of fertility in Caenorhabditis elegans lacking piRNAs is not caused by derepression of REs or other piRNA targets but, rather, is mediated by epigenetic silencing of all of the replicative histone genes. In the absence of piRNAs, downstream components of the piRNA pathway relocalize from germ granules and piRNA targets to histone mRNAs to synthesize antisense small RNAs (sRNAs) and induce transgenerational silencing. Removal of the downstream components of the piRNA pathway restores histone mRNA expression and fertility in piRNA mutants, and the inheritance of histone sRNAs in wild-type worms adversely affects their fertility for multiple generations. We conclude that sRNA-mediated silencing of histone genes impairs the fertility of piRNA mutants and may serve to maintain piRNAs across evolution.
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Affiliation(s)
- Giorgia Barucci
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
- Sorbonne Université, Collège doctoral, Paris, France
| | - Eric Cornes
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
| | - Meetali Singh
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
| | - Blaise Li
- Bioinformatics and Biostatistics Hub, C3BI, Institut Pasteur, USR 3756, CNRS, Paris, France
| | - Martino Ugolini
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
- Scuola Normale Superiore, Pisa, Italy
| | - Aleksei Samolygo
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
- Moscow Institute of Physics and Technology, Moscow, Russia
| | - Celine Didier
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
| | - Florent Dingli
- Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, Paris, France
| | - Damarys Loew
- Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, Paris, France
| | - Piergiuseppe Quarato
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France
- Sorbonne Université, Collège doctoral, Paris, France
| | - Germano Cecere
- Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, Institut Pasteur, UMR 3738, CNRS, Paris, France.
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29
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Lee CYS, Putnam A, Lu T, He S, Ouyang JPT, Seydoux G. Recruitment of mRNAs to P granules by condensation with intrinsically-disordered proteins. eLife 2020; 9:e52896. [PMID: 31975687 PMCID: PMC7007223 DOI: 10.7554/elife.52896] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 01/23/2020] [Indexed: 12/30/2022] Open
Abstract
RNA granules are protein/RNA condensates. How specific mRNAs are recruited to cytoplasmic RNA granules is not known. Here, we characterize the transcriptome and assembly of P granules, RNA granules in the C. elegans germ plasm. We find that P granules recruit mRNAs by condensation with the disordered protein MEG-3. MEG-3 traps mRNAs into non-dynamic condensates in vitro and binds to ~500 mRNAs in vivo in a sequence-independent manner that favors embryonic mRNAs with low ribosome coverage. Translational stress causes additional mRNAs to localize to P granules and translational activation correlates with P granule exit for two mRNAs coding for germ cell fate regulators. Localization to P granules is not required for translational repression but is required to enrich mRNAs in the germ lineage for robust germline development. Our observations reveal similarities between P granules and stress granules and identify intrinsically-disordered proteins as drivers of RNA condensation during P granule assembly.
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Affiliation(s)
- Chih-Yung S Lee
- HHMI and Department of Molecular Biology and GeneticsJohns Hopkins University School of MedicineBaltimoreUnited States
| | - Andrea Putnam
- HHMI and Department of Molecular Biology and GeneticsJohns Hopkins University School of MedicineBaltimoreUnited States
| | - Tu Lu
- HHMI and Department of Molecular Biology and GeneticsJohns Hopkins University School of MedicineBaltimoreUnited States
| | - ShuaiXin He
- HHMI and Department of Molecular Biology and GeneticsJohns Hopkins University School of MedicineBaltimoreUnited States
- Department of Biophysics and Biophysical ChemistryJohns Hopkins University School of MedicineBaltimoreUnited States
| | - John Paul T Ouyang
- HHMI and Department of Molecular Biology and GeneticsJohns Hopkins University School of MedicineBaltimoreUnited States
| | - Geraldine Seydoux
- HHMI and Department of Molecular Biology and GeneticsJohns Hopkins University School of MedicineBaltimoreUnited States
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30
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Marnik EA, Fuqua JH, Sharp CS, Rochester JD, Xu EL, Holbrook SE, Updike DL. Germline Maintenance Through the Multifaceted Activities of GLH/Vasa in Caenorhabditis elegans P Granules. Genetics 2019; 213:923-939. [PMID: 31506335 PMCID: PMC6827368 DOI: 10.1534/genetics.119.302670] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 09/03/2019] [Indexed: 02/07/2023] Open
Abstract
Vasa homologs are ATP-dependent DEAD-box helicases, multipotency factors, and critical components that specify and protect the germline. They regulate translation, amplify piwi-interacting RNAs (piRNAs), and act as RNA solvents; however, the limited availability of mutagenesis-derived alleles and their wide range of phenotypes have complicated their analysis. Now, with clustered regularly interspaced short palindromic repeats (CRISPR/Cas9), these limitations can be mitigated to determine why protein domains have been lost or retained throughout evolution. Here, we define the functional motifs of GLH-1/Vasa in Caenorhabditis elegans using 28 endogenous, mutant alleles. We show that GLH-1's helicase activity is required to retain its association with P granules. GLH-1 remains in P granules when changes are made outside of the helicase and flanking domains, but fertility is still compromised. Removal of the glycine-rich repeats from GLH proteins progressively diminishes P-granule wetting-like interactions at the nuclear periphery. Mass spectrometry of GLH-1-associated proteins implies conservation of a transient piRNA-amplifying complex, and reveals a novel affinity between GLH-1 and three structurally conserved PCI (26S Proteasome Lid, COP9, and eIF3) complexes or "zomes," along with a reciprocal aversion for assembled ribosomes and the 26S proteasome. These results suggest that P granules compartmentalize the cytoplasm to exclude large protein assemblies, effectively shielding associated transcripts from translation and associated proteins from turnover. Within germ granules, Vasa homologs may act as solvents, ensuring mRNA accessibility by small RNA surveillance and amplification pathways, and facilitating mRNA export through germ granules to initiate translation.
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Affiliation(s)
| | - J Heath Fuqua
- The Mount Desert Island Biological Laboratory, Bar Harbor, Maine 04672
- The College of the Atlantic, Bar Harbor, Maine 04609
| | - Catherine S Sharp
- The Mount Desert Island Biological Laboratory, Bar Harbor, Maine 04672
| | - Jesse D Rochester
- The Mount Desert Island Biological Laboratory, Bar Harbor, Maine 04672
- Graduate School of Biomedical Science and Engineering, University of Maine, Orono, Maine 04469
| | - Emily L Xu
- The Mount Desert Island Biological Laboratory, Bar Harbor, Maine 04672
- The College of William and Mary, Williamsburg, Virginia 23185
| | - Sarah E Holbrook
- The Mount Desert Island Biological Laboratory, Bar Harbor, Maine 04672
- Graduate School of Biomedical Science and Engineering, University of Maine, Orono, Maine 04469
- The Jackson Laboratory, Bar Harbor, Maine 04609
| | - Dustin L Updike
- The Mount Desert Island Biological Laboratory, Bar Harbor, Maine 04672
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31
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Lee HJ, Noormohammadi A, Koyuncu S, Calculli G, Simic MS, Herholz M, Trifunovic A, Vilchez D. Prostaglandin signals from adult germ stem cells delay somatic aging of Caenorhabditis elegans. Nat Metab 2019; 1:790-810. [PMID: 31485561 PMCID: PMC6726479 DOI: 10.1038/s42255-019-0097-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A moderate reduction of body temperature can induce a remarkable lifespan extension. Here we examine the link between cold temperature, germ line fitness and organismal longevity. We show that low temperature reduces age-associated exhaustion of germ stem cells (GSCs) in Caenorhabditis elegans, a process modulated by thermosensory neurons. Notably, robust self-renewal of adult GSCs delays reproductive aging and is required for extended lifespan at cold temperatures. These cells release prostaglandin E2 (PGE2) to induce cbs-1 expression in the intestine, increasing somatic production of hydrogen sulfide (H2S), a gaseous signaling molecule that prolongs lifespan. Whereas loss of adult GSCs reduces intestinal cbs-1 expression and cold-induced longevity, application of exogenous PGE2 rescues these phenotypes. Importantly, tissue-specific intestinal overexpression of cbs-1 mimics cold-temperature conditions and extends longevity even at warm temperatures. Thus, our results indicate that GSCs communicate with somatic tissues to coordinate extended reproductive capacity with longevity.
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Affiliation(s)
- Hyun Ju Lee
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Alireza Noormohammadi
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Seda Koyuncu
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Giuseppe Calculli
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Milos S Simic
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Marija Herholz
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Aleksandra Trifunovic
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - David Vilchez
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.
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32
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Asymmetric Inheritance of Cell Fate Determinants: Focus on RNA. Noncoding RNA 2019; 5:ncrna5020038. [PMID: 31075989 PMCID: PMC6630313 DOI: 10.3390/ncrna5020038] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/30/2019] [Accepted: 05/06/2019] [Indexed: 12/20/2022] Open
Abstract
During the last decade, and mainly primed by major developments in high-throughput sequencing technologies, the catalogue of RNA molecules harbouring regulatory functions has increased at a steady pace. Current evidence indicates that hundreds of mammalian RNAs have regulatory roles at several levels, including transcription, translation/post-translation, chromatin structure, and nuclear architecture, thus suggesting that RNA molecules are indeed mighty controllers in the flow of biological information. Therefore, it is logical to suggest that there must exist a series of molecular systems that safeguard the faithful inheritance of RNA content throughout cell division and that those mechanisms must be tightly controlled to ensure the successful segregation of key molecules to the progeny. Interestingly, whilst a handful of integral components of mammalian cells seem to follow a general pattern of asymmetric inheritance throughout division, the fate of RNA molecules largely remains a mystery. Herein, we will discuss current concepts of asymmetric inheritance in a wide range of systems, including prions, proteins, and finally RNA molecules, to assess overall the biological impact of RNA inheritance in cellular plasticity and evolutionary fitness.
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33
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Min H, Lee YU, Shim YH, Kawasaki I. Autophagy of germ-granule components, PGL-1 and PGL-3, contributes to DNA damage-induced germ cell apoptosis in C. elegans. PLoS Genet 2019; 15:e1008150. [PMID: 31125345 PMCID: PMC6534287 DOI: 10.1371/journal.pgen.1008150] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Accepted: 04/23/2019] [Indexed: 12/19/2022] Open
Abstract
Germ granules, termed P granules in nematode C. elegans, are the germline-specific cytoplasmic structures widely observed from worms to humans. P granules are known to have critical functions for postembryonic germline development likely through regulating RNA metabolism. They are localized at the perinuclear region of germ cells during most of the developmental stages. However, the biological significance of this specific localization remains elusive. PGL-1 and PGL-3, the defining components of P granules, were shown to be lost from the perinuclear region prior to germ cell apoptosis. Furthermore, this loss was shown to be significantly enhanced upon DNA damage. Here, we show that the removal of PGL-1 and PGL-3 from the perinuclear region following UV-induced DNA damage is significantly reduced in autophagy mutants. Autophagy was previously shown to be required for DNA damage-induced germ cell apoptosis. We show that the apoptosis defect of autophagy mutants is bypassed by depletion of pgl-1 or pgl-3. These findings are consistent with time-lapse observations of LGG-1 foci formation, showing that autophagy is activated following UV irradiation and that maximal accumulation of LGG-1 foci occurs before PGL-1 removal. We also show that some of the autophagy genes are transcriptionally activated following UV irradiation by CEP-1, the worm p53-like protein. Taken together, our results indicate that autophagy is required to remove the major P granule components, PGL-1 and PGL-3, and that their removal is required for the full induction of DNA damage-induced germ cell apoptosis. Our study contributes to a better understanding of germ cell apoptosis, a process that leads to the elimination of the vast majority of germ cells in various animals from worms to mammals.
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Affiliation(s)
- Hyemin Min
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Republic of Korea
| | - Yong-Uk Lee
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Republic of Korea
| | - Yhong-Hee Shim
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Republic of Korea
| | - Ichiro Kawasaki
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Republic of Korea
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34
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Miwa T, Inoue K, Sakamoto H. MRG-1 is required for both chromatin-based transcriptional silencing and genomic integrity of primordial germ cells in Caenorhabditis elegans. Genes Cells 2019; 24:377-389. [PMID: 30929290 DOI: 10.1111/gtc.12683] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 02/21/2019] [Accepted: 03/21/2019] [Indexed: 11/30/2022]
Abstract
In Caenorhabditis elegans, germline cells remain transcriptionally silenced during embryogenesis. The transcriptional silencing is achieved by two different mechanisms: One is the inhibition of RNA polymerase II in P2-P4 cells at the establishment stage, and another is chromatin-based silencing in two primordial germ cells (PGCs) at the maintenance stage; however, the molecular mechanism underlying chromatin-based silencing is less understood. We investigated the role of the chromodomain protein MRG-1, which is an essential maternal factor for germline development, in transcriptional silencing in PGCs. PGCs lacking maternal MRG-1 showed increased levels of two histone modifications (H3K4me2 and H4K16ac), which are epigenetic markers for active transcription, and precocious activation of germline promoters. Loss of MES-4, a H3K36 methyltransferase, also caused similar derepression of the germline genes in PGCs, suggesting that both MRG-1 and MES-4 function in chromatin-based silencing in PGCs. In addition, the mrg-1 null mutant showed abnormal chromosome structures and a decrease in homologous recombinase RAD-51 foci in PGCs, but the mes-4 null mutant did not show such phenotypes. Taken together, we propose that MRG-1 has two distinct functions: chromatin-based transcriptional silencing and preserving genomic integrity at the maintenance stage of PGCs.
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Affiliation(s)
- Takashi Miwa
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
| | - Kunio Inoue
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
| | - Hiroshi Sakamoto
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
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35
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Putnam A, Cassani M, Smith J, Seydoux G. A gel phase promotes condensation of liquid P granules in Caenorhabditis elegans embryos. Nat Struct Mol Biol 2019; 26:220-226. [PMID: 30833787 PMCID: PMC6668929 DOI: 10.1038/s41594-019-0193-2] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 01/25/2019] [Indexed: 01/20/2023]
Abstract
RNA granules are subcellular compartments that are proposed to form by liquid-liquid phase separation (LLPS), a thermodynamic process that partitions molecules between dilute liquid phases and condensed liquid phases. The mechanisms that localize liquid phases in cells, however, are not fully understood. P granules are RNA granules that form in the posterior of Caenorhabditis elegans embryos. Theoretical studies have suggested that spontaneous LLPS of the RNA-binding protein PGL-3 with RNA drives the assembly of P granules. We find that the PGL-3 phase is intrinsically labile and requires a second phase for stabilization in embryos. The second phase is formed by gel-like assemblies of the disordered protein MEG-3 that associate with liquid PGL-3 droplets in the embryo posterior. Co-assembly of gel phases and liquid phases confers local stability and long-range dynamics, both of which contribute to localized assembly of P granules. Our findings suggest that condensation of RNA granules can be regulated spatially by gel-like polymers that stimulate LLPS locally in the cytoplasm.
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Affiliation(s)
- Andrea Putnam
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Madeline Cassani
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Jarrett Smith
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
- Whitehead Institute, Massachusetts Institute of Technology, Boston, MA, USA
| | - Geraldine Seydoux
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
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36
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Zou L, Wu D, Zang X, Wang Z, Wu Z, Chen D. Construction of a germline-specific RNAi tool in C. elegans. Sci Rep 2019; 9:2354. [PMID: 30787374 PMCID: PMC6382888 DOI: 10.1038/s41598-019-38950-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/15/2019] [Indexed: 01/08/2023] Open
Abstract
Analysis of complex biological functions usually requires tissue-specific genetic manipulations in multicellular organisms. The C. elegans germline plays regulatory roles not only in reproduction, but also in metabolism, stress response and ageing. Previous studies have used mutants of rrf-1, which encodes an RNA-directed RNA polymerase, as a germline-specific RNAi tool. However, the rrf-1 mutants showed RNAi activities in somatic tissues. Here we constructed a germline-specific RNAi strain by combining an indel mutation of rde-1, which encodes an Argonaute protein that functions cell autonomously to ensure RNAi efficiency, and a single copy rde-1 transgene driven by the sun-1 germline-specific promoter. The germline RNAi efficiency and specificity are confirmed by RNAi phenocopy of known mutations, knockdown of GFP reporter expression, as well as quantitative RT-PCR measurement of tissue-specific mRNAs upon RNAi knockdown. The germline-specific RNAi strain shows no obvious deficiencies in reproduction, lipid accumulation, thermo-tolerance and life span compared to wild-type animals. By screening an RNAi sub-library of phosphatase genes, we identified novel regulators of thermo-tolerance. Together, we have created a useful tool that can facilitate the genetic analysis of germline-specific functions in C. elegans.
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Affiliation(s)
- Lina Zou
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center, Nanjing University, 12 Xuefu Rd, Pukou, Nanjing, Jiangsu, 210061, China
| | - Di Wu
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center, Nanjing University, 12 Xuefu Rd, Pukou, Nanjing, Jiangsu, 210061, China
| | - Xiao Zang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center, Nanjing University, 12 Xuefu Rd, Pukou, Nanjing, Jiangsu, 210061, China
| | - Zi Wang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center, Nanjing University, 12 Xuefu Rd, Pukou, Nanjing, Jiangsu, 210061, China
| | - Zixing Wu
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center, Nanjing University, 12 Xuefu Rd, Pukou, Nanjing, Jiangsu, 210061, China
| | - Di Chen
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center, Nanjing University, 12 Xuefu Rd, Pukou, Nanjing, Jiangsu, 210061, China.
- Institute for Brain Sciences, Nanjing University, Nanjing, China.
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37
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Whittle CA, Extavour CG. Contrasting patterns of molecular evolution in metazoan germ line genes. BMC Evol Biol 2019; 19:53. [PMID: 30744572 PMCID: PMC6371493 DOI: 10.1186/s12862-019-1363-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 01/14/2019] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Germ lines are the cell lineages that give rise to the sperm and eggs in animals. The germ lines first arise from primordial germ cells (PGCs) during embryogenesis: these form from either a presumed derived mode of preformed germ plasm (inheritance) or from an ancestral mechanism of inductive cell-cell signalling (induction). Numerous genes involved in germ line specification and development have been identified and functionally studied. However, little is known about the molecular evolutionary dynamics of germ line genes in metazoan model systems. RESULTS Here, we studied the molecular evolution of germ line genes within three metazoan model systems. These include the genus Drosophila (N=34 genes, inheritance), the fellow insect Apis (N=30, induction), and their more distant relative Caenorhabditis (N=23, inheritance). Using multiple species and established phylogenies in each genus, we report that germ line genes exhibited marked variation in the constraint on protein sequence divergence (dN/dS) and codon usage bias (CUB) within each genus. Importantly, we found that de novo lineage-specific inheritance (LSI) genes in Drosophila (osk, pgc) and in Caenorhabditis (pie-1, pgl-1), which are essential to germ plasm functions under the derived inheritance mode, displayed rapid protein sequence divergence relative to the other germ line genes within each respective genus. We show this may reflect the evolution of specialized germ plasm functions and/or low pleiotropy of LSI genes, features not shared with other germ line genes. In addition, we observed that the relative ranking of dN/dS and of CUB between genera were each more strongly correlated between Drosophila and Caenorhabditis, from different phyla, than between Drosophila and its insect relative Apis, suggesting taxonomic differences in how germ line genes have evolved. CONCLUSIONS Taken together, the present results advance our understanding of the evolution of animal germ line genes within three well-known metazoan models. Further, the findings provide insights to the molecular evolution of germ line genes with respect to LSI status, pleiotropy, adaptive evolution as well as PGC-specification mode.
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Affiliation(s)
- Carrie A Whittle
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA, 02138, USA
| | - Cassandra G Extavour
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA, 02138, USA.
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA, 02138, USA.
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Lebedeva LA, Yakovlev KV, Kozlov EN, Schedl P, Deshpande G, Shidlovskii YV. Transcriptional quiescence in primordial germ cells. Crit Rev Biochem Mol Biol 2018; 53:579-595. [PMID: 30280955 PMCID: PMC8729227 DOI: 10.1080/10409238.2018.1506733] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/09/2018] [Accepted: 07/27/2018] [Indexed: 12/31/2022]
Abstract
In most animal species, newly formed primordial germ cells (PGCs) acquire the special characteristics that distinguish them from the surrounding somatic cells. Proper fate specification of the PGCs is coupled with transcriptional quiescence, whether they are segregated by determinative or inductive mechanisms. Inappropriate differentiation of PGCs into somatic cells is thought to be prevented due to repression of RNA polymerase (Pol) II-dependent transcription. In the case of a determinative mode of PGC formation (Drosophila, Caenorhabditis elegans, etc.), there is a broad downregulation of Pol II activity. By contrast, PGCs display only gene-specific repression in organisms that rely on inductive signaling-based mechanism (e.g., mice). In addition to the global block of Pol II activity in PGCs, gene expression can be suppressed in other ways, such as chromatin remodeling and Piwi-mediated RNAi. Here, we discuss the mechanisms responsible for the transcriptionally silent state of PGCs in common experimental animals, such as Drosophila, C. elegans, Danio rerio, Xenopus, and mouse. While a PGC-specific downregulation of transcription is a common feature among these organisms, the diverse nature of underlying mechanisms suggests that this functional trait likely evolved independently on several instances. We discuss the possible biological relevance of these silencing mechanisms vis-a-vis fate determination of PGCs.
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Affiliation(s)
| | - Konstantin V. Yakovlev
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Laboratory of Cytotechnology, National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia
| | - Eugene N. Kozlov
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Paul Schedl
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Department of Molecular Biology, Princeton University, Princeton, USA
| | - Girish Deshpande
- Department of Molecular Biology, Princeton University, Princeton, USA
| | - Yulii V. Shidlovskii
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- I.M. Sechenov First Moscow State Medical University, Moscow, Russia
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Krishnakumar P, Riemer S, Perera R, Lingner T, Goloborodko A, Khalifa H, Bontems F, Kaufholz F, El-Brolosy MA, Dosch R. Functional equivalence of germ plasm organizers. PLoS Genet 2018; 14:e1007696. [PMID: 30399145 PMCID: PMC6219760 DOI: 10.1371/journal.pgen.1007696] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 09/16/2018] [Indexed: 11/18/2022] Open
Abstract
The proteins Oskar (Osk) in Drosophila and Bucky ball (Buc) in zebrafish act as germ plasm organizers. Both proteins recapitulate germ plasm activities but seem to be unique to their animal groups. Here, we discover that Osk and Buc show similar activities during germ cell specification. Drosophila Osk induces additional PGCs in zebrafish. Surprisingly, Osk and Buc do not show homologous protein motifs that would explain their related function. Nonetheless, we detect that both proteins contain stretches of intrinsically disordered regions (IDRs), which seem to be involved in protein aggregation. IDRs are known to rapidly change their sequence during evolution, which might obscure biochemical interaction motifs. Indeed, we show that Buc binds to the known Oskar interactors Vasa protein and nanos mRNA indicating conserved biochemical activities. These data provide a molecular framework for two proteins with unrelated sequence but with equivalent function to assemble a conserved core-complex nucleating germ plasm. Multicellular organisms use gametes for their propagation. Gametes are formed from germ cells, which are specified during embryogenesis in some animals by the inheritance of RNP granules known as germ plasm. Transplantation of germ plasm induces extra germ cells, whereas germ plasm ablation leads to the loss of gametes and sterility. Therefore, germ plasm is key for germ cell formation and reproduction. However, the molecular mechanisms of germ cell specification by germ plasm in the vertebrate embryo remain an unsolved question. Proteins, which assemble the germ plasm, are known as germ plasm organizers. Here, we show that the two germ plasm organizers Oskar from the fly and Bucky ball from the fish show similar functions by using a cross species approach. Both are intrinsically disordered proteins, which rapidly changed their sequence during evolution. Moreover, both proteins still interact with conserved components of the germ cell specification pathway. These data might provide a first example of two proteins with the same biological role, but distinct sequence.
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Affiliation(s)
- Pritesh Krishnakumar
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Stephan Riemer
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Roshan Perera
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Thomas Lingner
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Alexander Goloborodko
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Hazem Khalifa
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Franck Bontems
- Laboratory of Metabolism, Department of Internal Medicine Specialties, Faculty of Medicine, University of Geneva, Switzerland
| | - Felix Kaufholz
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Mohamed A. El-Brolosy
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Roland Dosch
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
- Institute of Human Genetics, University Medical Center, Göttingen, Germany
- * E-mail:
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40
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Wu E, Vashisht AA, Chapat C, Flamand MN, Cohen E, Sarov M, Tabach Y, Sonenberg N, Wohlschlegel J, Duchaine TF. A continuum of mRNP complexes in embryonic microRNA-mediated silencing. Nucleic Acids Res 2018; 45:2081-2098. [PMID: 28204614 PMCID: PMC5389717 DOI: 10.1093/nar/gkw872] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 09/21/2016] [Accepted: 09/28/2016] [Indexed: 12/12/2022] Open
Abstract
MicroRNAs (miRNAs) impinge on the translation and stability of their target mRNAs, and play key roles in development, homeostasis and disease. The gene regulation mechanisms they instigate are largely mediated through the CCR4–NOT deadenylase complex, but the molecular events that occur on target mRNAs are poorly resolved. We observed a broad convergence of interactions of germ granule and P body mRNP components on AIN-1/GW182 and NTL-1/CNOT1 in Caenorhabditis elegans embryos. We show that the miRISC progressively matures on the target mRNA from a scanning form into an effector mRNP particle by sequentially recruiting the CCR4–NOT complex, decapping and decay, or germ granule proteins. Finally, we implicate intrinsically disordered proteins, key components in mRNP architectures, in the embryonic function of lsy-6 miRNA. Our findings define dynamic steps of effector mRNP assembly in miRNA-mediated silencing, and identify a functional continuum between germ granules and P bodies in the C. elegans embryo.
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Affiliation(s)
| | - Ajay A Vashisht
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Clément Chapat
- Department of Biochemistry and Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3G 1Y6 Canada
| | - Mathieu N Flamand
- Department of Biochemistry and Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3G 1Y6 Canada
| | - Emiliano Cohen
- Department of Developmental Biology and Cancer Research, The Institute For Medical Research-Israel-Canada, The Hebrew University Hadassah Medical School, Jerusalem 91120, Israel
| | - Mihail Sarov
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Yuval Tabach
- Department of Developmental Biology and Cancer Research, The Institute For Medical Research-Israel-Canada, The Hebrew University Hadassah Medical School, Jerusalem 91120, Israel
| | - Nahum Sonenberg
- Department of Biochemistry and Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3G 1Y6 Canada
| | - James Wohlschlegel
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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41
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Distinct Roles of Two Histone Methyltransferases in Transmitting H3K36me3-Based Epigenetic Memory Across Generations in Caenorhabditis elegans. Genetics 2018; 210:969-982. [PMID: 30217796 PMCID: PMC6218224 DOI: 10.1534/genetics.118.301353] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 09/04/2018] [Indexed: 02/07/2023] Open
Abstract
Epigenetic information contributes to proper gene expression and development, and can be transmitted not only through mitotic divisions but also from parents to progeny. We investigated the roles in epigenetic inheritance of MES-4 and MET-1, the two Caenorhabditis elegans enzymes that methylate H3K36 (histone H3 Lys 36). Mass spectrometry analysis confirmed immunostaining results showing that both MES-4 and MET-1 catalyze H3K36me3. In the adult germline, MES-4 is enriched in the distal mitotic zone and MET-1 is enriched in the meiotic pachytene zone. Embryos inherit H3K36me3-marked chromosomes from both the oocyte and sperm, and a maternal load of MES-4 and MET-1. Maternal MES-4 quickly associates with sperm chromosomes; that association requires that the sperm chromosomes bear H3K36me3, suggesting that MES-4 is recruited to chromosomes by preexisting H3K36me3. In embryos that inherit H3K36me3-positive oocyte chromosomes and H3K36me3-negative sperm chromosomes, MES-4 and H3K36me3 are maintained on only a subset of chromosomes until at least the 32-cell stage, likely because MES-4 propagates H3K36me3 on regions of the genome with preexisting H3K36me3. In embryos lacking MES-4, H3K36me3 levels on chromosomes drop precipitously postfertilization. In contrast to the relatively high levels of MES-4 in early-stage embryos, MET-1 levels are low at early stages and start increasing by the ∼26-cell stage, consistent with expression from the zygotic genome. Our findings support the model that MET-1 mediates transcription-coupled H3K36me3 in the parental germline and transcriptionally active embryos, and that MES-4 transmits an epigenetic memory of H3K36me3 across generations and through early embryo cell divisions by maintaining inherited patterns of H3K36me3.
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42
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Alberti S, Saha S, Woodruff JB, Franzmann TM, Wang J, Hyman AA. A User's Guide for Phase Separation Assays with Purified Proteins. J Mol Biol 2018; 430:4806-4820. [PMID: 29944854 PMCID: PMC6215329 DOI: 10.1016/j.jmb.2018.06.038] [Citation(s) in RCA: 158] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 06/12/2018] [Accepted: 06/19/2018] [Indexed: 11/16/2022]
Abstract
The formation of membrane-less organelles and compartments by protein phase separation is an important way in which cells organize their cytoplasm and nucleoplasm. In vitro phase separation assays with purified proteins have become the standard way to investigate proteins that form membrane-less compartments. By now, various proteins have been purified and tested for their ability to phase separate and form liquid condensates in vitro. However, phase-separating proteins are often aggregation-prone and difficult to purify and handle. As a consequence, the results from phase separation assays often differ between labs and are not easily reproduced. Thus, there is an urgent need for high-quality proteins, standardized procedures, and generally agreed-upon practices for protein purification and conducting phase separation assays. This paper provides protocols for protein purification and guides the user through the practicalities of in vitro protein phase separation assays, including best-practice approaches and pitfalls to avoid. We believe that this compendium of protocols and practices will provide a useful resource for scientists studying the phase behavior of proteins.
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Affiliation(s)
- Simon Alberti
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
| | - Shambaditya Saha
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
| | - Jeffrey B Woodruff
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Titus M Franzmann
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Jie Wang
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Anthony A Hyman
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
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43
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Cao J, Packer JS, Ramani V, Cusanovich DA, Huynh C, Daza R, Qiu X, Lee C, Furlan SN, Steemers FJ, Adey A, Waterston RH, Trapnell C, Shendure J. Comprehensive single-cell transcriptional profiling of a multicellular organism. Science 2017; 357:661-667. [PMID: 28818938 DOI: 10.1126/science.aam8940] [Citation(s) in RCA: 826] [Impact Index Per Article: 118.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 05/12/2017] [Accepted: 07/19/2017] [Indexed: 12/14/2022]
Abstract
To resolve cellular heterogeneity, we developed a combinatorial indexing strategy to profile the transcriptomes of single cells or nuclei, termed sci-RNA-seq (single-cell combinatorial indexing RNA sequencing). We applied sci-RNA-seq to profile nearly 50,000 cells from the nematode Caenorhabditis elegans at the L2 larval stage, which provided >50-fold "shotgun" cellular coverage of its somatic cell composition. From these data, we defined consensus expression profiles for 27 cell types and recovered rare neuronal cell types corresponding to as few as one or two cells in the L2 worm. We integrated these profiles with whole-animal chromatin immunoprecipitation sequencing data to deconvolve the cell type-specific effects of transcription factors. The data generated by sci-RNA-seq constitute a powerful resource for nematode biology and foreshadow similar atlases for other organisms.
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Affiliation(s)
- Junyue Cao
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.,Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - Jonathan S Packer
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Vijay Ramani
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | | | - Chau Huynh
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Riza Daza
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Xiaojie Qiu
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.,Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - Choli Lee
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Scott N Furlan
- Ben Towne Center for Childhood Cancer Research, Seattle Children's Research Institute, Seattle, WA, USA.,Department of Pediatrics, University of Washington, Seattle, WA, USA.,Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | | | - Andrew Adey
- Department of Molecular & Medical Genetics, Oregon Health & Science University, Portland, OR, USA.,Knight Cardiovascular Institute, Portland, OR, USA
| | - Robert H Waterston
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
| | - Cole Trapnell
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA, USA. .,Howard Hughes Medical Institute, Seattle, WA, USA
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44
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Cao J, Packer JS, Ramani V, Cusanovich DA, Huynh C, Daza R, Qiu X, Lee C, Furlan SN, Steemers FJ, Adey A, Waterston RH, Trapnell C, Shendure J. Comprehensive single-cell transcriptional profiling of a multicellular organism. Science 2017. [DOI: 10.1126/science.aam8940 order by 10746--] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Junyue Cao
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - Jonathan S. Packer
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Vijay Ramani
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | | | - Chau Huynh
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Riza Daza
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Xiaojie Qiu
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - Choli Lee
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Scott N. Furlan
- Ben Towne Center for Childhood Cancer Research, Seattle Children’s Research Institute, Seattle, WA, USA
- Department of Pediatrics, University of Washington, Seattle, WA, USA
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | | | - Andrew Adey
- Department of Molecular & Medical Genetics, Oregon Health & Science University, Portland, OR, USA
- Knight Cardiovascular Institute, Portland, OR, USA
| | | | - Cole Trapnell
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Howard Hughes Medical Institute, Seattle, WA, USA
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45
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Zhang G, Lin L, Qi D, Zhang H. The composition of a protein aggregate modulates the specificity and efficiency of its autophagic degradation. Autophagy 2017; 13:1487-1495. [PMID: 28806108 DOI: 10.1080/15548627.2017.1339843] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The mechanism underlying autophagic degradation of a protein aggregate remains largely unknown. A family of receptor proteins that simultaneously bind to the cargo and the Atg8 family of autophagy proteins (such as the MAP1LC3/LC3 subfamily) has been shown to confer cargo selectivity. The selectivity and efficiency of protein aggregate removal is also modulated by scaffold proteins that interact with receptor proteins and ATG proteins. During C. elegans embryogenesis, autophagic clearance of the cargoes PGL-1 and PGL-3 requires the receptor protein SEPA-1 and the scaffold protein EPG-2. SEPA-1 and EPG-2 also form aggregates that are degraded by autophagy. Here we investigated the effect of composition and organization of PGL granules on their autophagic degradation. We found that depletion of PGL-1 or PGL-3 facilitates the degradation of SEPA-1 and EPG-2. Removal of EPG-2 is also promoted when SEPA-1 is absent. Depletion of PGL-1 or PGL-3 renders the degradation of SEPA-1 independent of EPG-2. We further showed that overexpression of SEPA-1 or EPG-2 as well as SQST-1 or EPG-7 (scaffold protein), which belong to different classes of aggregate, has no evident effect on the degradation of the other type. Our results indicate that the composition and organization of protein aggregates provide another layer of regulation to modulate degradation efficiency.
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Affiliation(s)
- Gangming Zhang
- a National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , Beijing , China
| | - Long Lin
- a National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , Beijing , China
| | - Di Qi
- a National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , Beijing , China
| | - Hong Zhang
- a National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , Beijing , China.,b College of Life Sciences , University of Chinese Academy of Sciences , Beijing , China
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Germ Granules Prevent Accumulation of Somatic Transcripts in the Adult Caenorhabditis elegans Germline. Genetics 2017; 206:163-178. [PMID: 28258184 DOI: 10.1534/genetics.116.198549] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 03/01/2017] [Indexed: 11/18/2022] Open
Abstract
The germ cells of multicellular organisms protect their developmental potential through specialized mechanisms. A shared feature of germ cells from worms to humans is the presence of nonmembrane-bound, ribonucleoprotein organelles called germ granules. Depletion of germ granules in Caenorhabditis elegans (i.e., P granules) leads to sterility and, in some germlines, expression of the neuronal transgene unc-119::gfp and the muscle myosin MYO-3 Thus, P granules are hypothesized to maintain germ cell totipotency by preventing somatic development, although the mechanism by which P granules carry out this function is unknown. In this study, we performed transcriptome and single molecule RNA-FISH analyses of dissected P granule-depleted gonads at different developmental stages. Our results demonstrate that P granules are necessary for adult germ cells to downregulate spermatogenesis RNAs and to prevent the accumulation of numerous soma-specific RNAs. P granule-depleted gonads that express the unc-119::gfp transgene also express many other genes involved in neuronal development and concomitantly lose expression of germ cell fate markers. Finally, we show that removal of either of two critical P-granule components, PGL-1 or GLH-1, is sufficient to cause germ cells to express UNC-119::GFP and MYO-3 and to display RNA accumulation defects similar to those observed after depletion of P granules. Our data identify P granules as critical modulators of the germline transcriptome and guardians of germ cell fate.
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47
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Al-Amin M, Min H, Shim YH, Kawasaki I. Somatically expressed germ-granule components, PGL-1 and PGL-3, repress programmed cell death in C. elegans. Sci Rep 2016; 6:33884. [PMID: 27650246 PMCID: PMC5030653 DOI: 10.1038/srep33884] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 09/05/2016] [Indexed: 01/15/2023] Open
Abstract
We previously reported that germline apoptosis in C. elegans increased by loss of PGL-1 and PGL-3, members of a family of constitutive germ-granule components, from germ cells in adult hermaphrodite gonads. In this study, we found that somatic apoptosis was reduced in synthetic multivulva class B (synMuv B) mutants due to ectopic expression of PGL-1 and PGL-3 in the soma. In synMuv B-mutant somatic cells, CED-4 expression level was reduced due to ectopic expression of PGL-1. Furthermore, in contrast to wild type, somatic apoptosis in synMuv B mutants increased following DNA damage in a SIR-2.1-dependent manner. Intriguingly, somatic apoptosis was repressed not only in synMuv B mutants but also by ectopically expressing pgl-1 and/or pgl-3 transgenes in wild-type somatic cells. Our study demonstrates that germ-granule components, PGL-1 and PGL-3, can serve as negative regulators of apoptosis not only in the germline but also in the soma in C. elegans.
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Affiliation(s)
- Mohammad Al-Amin
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Republic of Korea
| | - Hyemin Min
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Republic of Korea
| | - Yhong-Hee Shim
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Republic of Korea
| | - Ichiro Kawasaki
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Republic of Korea
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48
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RNAi Screen Identifies Novel Regulators of RNP Granules in the Caenorhabditis elegans Germ Line. G3-GENES GENOMES GENETICS 2016; 6:2643-54. [PMID: 27317775 PMCID: PMC4978917 DOI: 10.1534/g3.116.031559] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Complexes of RNA and RNA binding proteins form large-scale supramolecular structures under many cellular contexts. In Caenorhabditis elegans, small germ granules are present in the germ line that share characteristics with liquid droplets that undergo phase transitions. In meiotically-arrested oocytes of middle-aged hermaphrodites, the germ granules appear to aggregate or condense into large assemblies of RNA-binding proteins and maternal mRNAs. Prior characterization of the assembly of large-scale RNP structures via candidate approaches has identified a small number of regulators of phase transitions in the C. elegans germ line; however, the assembly, function, and regulation of these large RNP assemblies remain incompletely understood. To identify genes that promote remodeling and assembly of large RNP granules in meiotically-arrested oocytes, we performed a targeted, functional RNAi screen and identified over 300 genes that regulate the assembly of the RNA-binding protein MEX-3 into large granules. Among the most common GO classes are several categories related to RNA biology, as well as novel categories such as cell cortex, ER, and chromosome segregation. We found that arrested oocytes that fail to localize MEX-3 into cortical granules display reduced oocyte quality, consistent with the idea that the larger RNP assemblies promote oocyte quality when fertilization is delayed. Interestingly, a relatively small number of genes overlap with the regulators of germ granule assembly during normal development, or with the regulators of solid RNP granules in cgh-1 oocytes, suggesting fundamental differences in the regulation of RNP granule phase transitions during meiotic arrest.
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49
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Mainpal R, Yanowitz JL. A twist of fate: How a meiotic protein is providing new perspectives on germ cell development. WORM 2016; 5:e1175259. [PMID: 27383565 PMCID: PMC4911978 DOI: 10.1080/21624054.2016.1175259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 03/18/2016] [Accepted: 03/30/2016] [Indexed: 10/22/2022]
Abstract
The molecular pathways that govern how germ line fate is acquired is an area of intense investigation that has major implications for the development of assisted reproductive technologies, infertility interventions, and treatment of germ cell cancers. Transcriptional repression has emerged as a primary mechanism to ensure suppression of somatic growth programs in primordial germ cells. In this commentary, we address how xnd-1 illuminates our understanding of transcriptional repression and how it is coordinated with the germ cell differentiation program. We recently identified xnd-1 as a novel, early determinant of germ cell fates in Caenorhabditis elegans. Our study revealed that XND-1 is maternally deposited into early embryos where it is selectively enriched in the germ lineage and then exclusively found on chromatin in the germ lineage throughout development and into adulthood when it dissociates from chromosomes in late pachytene. This localization is consistent with a range of interesting germ cell defects that suggest xnd-1 is a pivotal determinant of germ cell characteristics. Loss of xnd-1 results in a unique "one PGC (primordial germ cell)" phenotype due to G2 cell cycle arrest of the germline precursor blastomere, P4, which predisposes the animal and its progeny for reduced fecundity. The sterility in xnd-1 mutants is correlated with an increase in the transcriptional activation-associated histone modification, dimethylation of histone H3 lysine 4 (H3K4me2), and aberrant expression of somatic transgenes but overlapping roles with nos-2 and nos-1 suggest that transcriptional repression is achieved by multiple redundant mechanisms.
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Affiliation(s)
- Rana Mainpal
- Department of Obstetrics, Magee-Womens Research Institute, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Judith L. Yanowitz
- Department of Obstetrics, Magee-Womens Research Institute, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Reevaluation of whether a soma-to-germ-line transformation extends lifespan in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2016; 113:3591-6. [PMID: 26976573 DOI: 10.1073/pnas.1523402113] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The germ lineage is considered to be immortal. In the quest to extend lifespan, a possible strategy is to drive germ-line traits in somatic cells, to try to confer some of the germ lineage's immortality on the somatic body. Notably, a study in Caenorhabditis elegans suggested that expression of germ-line genes in the somatic cells of long-lived daf-2 mutants confers some of daf-2's long lifespan. Specifically, mRNAs encoding components of C. elegans germ granules (P granules) were up-regulated in daf-2 mutant worms, and knockdown of individual P-granule and other germ-line genes in daf-2 young adults modestly reduced their lifespan. We investigated the contribution of a germ-line program to daf-2's long lifespan and also tested whether other mutants known to express germ-line genes in their somatic cells are long-lived. Our key findings are as follows. (i) We could not detect P-granule proteins in the somatic cells of daf-2 mutants by immunostaining or by expression of a P-granule transgene. (ii) Whole-genome transcript profiling of animals lacking a germ line revealed that germ-line transcripts are not up-regulated in the soma of daf-2 worms compared with the soma of control worms. (iii) Simultaneous removal of multiple P-granule proteins or the entire germ-line program from daf-2 worms did not reduce their lifespan. (iv) Several mutants that robustly express a broad spectrum of germ-line genes in their somatic cells are not long-lived. Together, our findings argue against the hypothesis that acquisition of a germ-cell program in somatic cells increases lifespan and contributes to daf-2's long lifespan.
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