1
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Connors CQ, Mauro MS, Wiles JT, Countryman AD, Martin SL, Lacroix B, Shirasu-Hiza M, Dumont J, Kasza KE, Davies TR, Canman JC. Germ fate determinants protect germ precursor cell division by reducing septin and anillin levels at the cell division plane. Mol Biol Cell 2024; 35:ar94. [PMID: 38696255 DOI: 10.1091/mbc.e24-02-0096-t] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2024] Open
Abstract
Animal cell cytokinesis, or the physical division of one cell into two, is thought to be driven by constriction of an actomyosin contractile ring at the division plane. The mechanisms underlying cell type-specific differences in cytokinesis remain unknown. Germ cells are totipotent cells that pass genetic information to the next generation. Previously, using formincyk-1(ts) mutant Caenorhabditis elegans 4-cell embryos, we found that the P2 germ precursor cell is protected from cytokinesis failure and can divide with greatly reduced F-actin levels at the cell division plane. Here, we identified two canonical germ fate determinants required for P2-specific cytokinetic protection: PIE-1 and POS-1. Neither has been implicated previously in cytokinesis. These germ fate determinants protect P2 cytokinesis by reducing the accumulation of septinUNC-59 and anillinANI-1 at the division plane, which here act as negative regulators of cytokinesis. These findings may provide insight into the regulation of cytokinesis in other cell types, especially in stem cells with high potency.
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Affiliation(s)
- Caroline Q Connors
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032
| | - Michael S Mauro
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032
| | - J Tristian Wiles
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Andrew D Countryman
- Department of Biomedical Engineering, Columbia University, New York, NY 10027
| | - Sophia L Martin
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032
| | - Benjamin Lacroix
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Université de Montpellier, CNRS, Centre de Recherche en Biologie Cellulaire de Montpellier, UMR 5237 Montpellier, France
| | - Mimi Shirasu-Hiza
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032
| | - Julien Dumont
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Karen E Kasza
- Department of Mechanical Engineering, Columbia University, New York, NY 10027
| | - Timothy R Davies
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032
- Department of Biosciences, Durham University, Durham DH1 3LE, UK
| | - Julie C Canman
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032
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2
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Liu J, Murray JI. Mechanisms of lineage specification in Caenorhabditis elegans. Genetics 2023; 225:iyad174. [PMID: 37847877 DOI: 10.1093/genetics/iyad174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 09/18/2023] [Indexed: 10/19/2023] Open
Abstract
The studies of cell fate and lineage specification are fundamental to our understanding of the development of multicellular organisms. Caenorhabditis elegans has been one of the premiere systems for studying cell fate specification mechanisms at single cell resolution, due to its transparent nature, the invariant cell lineage, and fixed number of somatic cells. We discuss the general themes and regulatory mechanisms that have emerged from these studies, with a focus on somatic lineages and cell fates. We next review the key factors and pathways that regulate the specification of discrete cells and lineages during embryogenesis and postembryonic development; we focus on transcription factors and include numerous lineage diagrams that depict the expression of key factors that specify embryonic founder cells and postembryonic blast cells, and the diverse somatic cell fates they generate. We end by discussing some future perspectives in cell and lineage specification.
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Affiliation(s)
- Jun Liu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - John Isaac Murray
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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3
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Connors CQ, Mauro MS, Tristian Wiles J, Countryman AD, Martin SL, Lacroix B, Shirasu-Hiza M, Dumont J, Kasza KE, Davies TR, Canman JC. Germ fate determinants protect germ precursor cell division by restricting septin and anillin levels at the division plane. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.17.566773. [PMID: 38014027 PMCID: PMC10680835 DOI: 10.1101/2023.11.17.566773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Animal cell cytokinesis, or the physical division of one cell into two, is thought to be driven by constriction of an actomyosin contractile ring at the division plane. The mechanisms underlying cell type-specific differences in cytokinesis remain unknown. Germ cells are totipotent cells that pass genetic information to the next generation. Previously, using formin cyk-1 (ts) mutant C. elegans embryos, we found that the P2 germ precursor cell is protected from cytokinesis failure and can divide without detectable F-actin at the division plane. Here, we identified two canonical germ fate determinants required for P2-specific cytokinetic protection: PIE-1 and POS-1. Neither has been implicated previously in cytokinesis. These germ fate determinants protect P2 cytokinesis by reducing the accumulation of septin UNC-59 and anillin ANI-1 at the division plane, which here act as negative regulators of cytokinesis. These findings may provide insight into cytokinetic regulation in other cell types, especially in stem cells with high potency.
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4
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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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5
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Belew MD, Chien E, Michael WM. Characterization of factors that underlie transcriptional silencing in C. elegans oocytes. PLoS Genet 2023; 19:e1010831. [PMID: 37478128 PMCID: PMC10395837 DOI: 10.1371/journal.pgen.1010831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 06/15/2023] [Indexed: 07/23/2023] Open
Abstract
While it has been appreciated for decades that prophase-arrested oocytes are transcriptionally silenced on a global level, the molecular pathways that promote silencing have remained elusive. Previous work in C. elegans has shown that both topoisomerase II (TOP-2) and condensin II collaborate with the H3K9me heterochromatin pathway to silence gene expression in the germline during L1 starvation, and that the PIE-1 protein silences the genome in the P-lineage of early embryos. Here, we show that all three of these silencing systems, TOP-2/condensin II, H3K9me, and PIE-1, are required for transcriptional repression in oocytes. We find that H3K9me3 marks increase dramatically on chromatin during silencing, and that silencing is under cell cycle control. We also find that PIE-1 localizes to the nucleolus just prior to silencing, and that nucleolar dissolution during silencing is dependent on TOP-2/condensin II. Our data identify both the molecular components and the trigger for genome silencing in oocytes and establish a link between PIE-1 nucleolar residency and its ability to repress transcription.
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Affiliation(s)
- Mezmur D Belew
- Department of Biological Sciences, Molecular and Computational Biology Section, University of Southern California, Los Angeles, California, United States of America
| | - Emilie Chien
- Department of Biological Sciences, Molecular and Computational Biology Section, University of Southern California, Los Angeles, California, United States of America
| | - W Matthew Michael
- Department of Biological Sciences, Molecular and Computational Biology Section, University of Southern California, Los Angeles, California, United States of America
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6
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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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7
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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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8
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Webster AK, Chitrakar R, Taylor SM, Baugh LR. Alternative somatic and germline gene-regulatory strategies during starvation-induced developmental arrest. Cell Rep 2022; 41:111473. [PMID: 36223742 PMCID: PMC9608353 DOI: 10.1016/j.celrep.2022.111473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 07/18/2022] [Accepted: 09/20/2022] [Indexed: 11/16/2022] Open
Abstract
Nutrient availability governs growth and quiescence, and many animals arrest development when starved. Using C. elegans L1 arrest as a model, we show that gene expression changes deep into starvation. Surprisingly, relative expression of germline-enriched genes increases for days. We conditionally degrade the large subunit of RNA polymerase II using the auxin-inducible degron system and analyze absolute expression levels. We find that somatic transcription is required for survival, but the germline maintains transcriptional quiescence. Thousands of genes are continuously transcribed in the soma, though their absolute abundance declines, such that relative expression of germline transcripts increases given extreme transcript stability. Aberrantly activating transcription in starved germ cells compromises reproduction, demonstrating important physiological function of transcriptional quiescence. This work reveals alternative somatic and germline gene-regulatory strategies during starvation, with the soma maintaining a robust transcriptional response to support survival and the germline maintaining transcriptional quiescence to support future reproductive success. Webster et al. show that the transcriptional response to starvation is mounted early in larval somatic cells supporting survival but that it wanes over time. In contrast, they show that the germline remains transcriptionally quiescent deep into starvation, supporting reproductive potential, while maintaining its transcriptome via transcript stability.
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Affiliation(s)
- Amy K. Webster
- Department of Biology, Duke University, Durham, NC 27708, USA,Present address: Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Rojin Chitrakar
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Seth M. Taylor
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - L. Ryan Baugh
- Department of Biology, Duke University, Durham, NC 27708, USA,Center for Genomic and Computational Biology, Duke University, Durham, NC 27708, USA,Lead contact,Correspondence:
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9
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Fasimoye RY, Spencer R, Soto-Martin E, Eijlers P, Elmassoudi H, Brivio S, Mangana C, Sabele V, Rechtorikova R, Wenzel M, Connolly B, Pettitt J, Müller B. A novel, essential trans-splicing protein connects the nematode SL1 snRNP to the CBC-ARS2 complex. Nucleic Acids Res 2022; 50:7591-7607. [PMID: 35736244 PMCID: PMC9303266 DOI: 10.1093/nar/gkac534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 06/01/2022] [Accepted: 06/07/2022] [Indexed: 11/29/2022] Open
Abstract
Spliced leader trans-splicing is essential for gene expression in many eukaryotes. To elucidate the molecular mechanism of this process, we characterise the molecules associated with the Caenorhabditis elegans major spliced leader snRNP (SL1 snRNP), which donates the spliced leader that replaces the 5' untranslated region of most pre-mRNAs. Using a GFP-tagged version of the SL1 snRNP protein SNA-1 created by CRISPR-mediated genome engineering, we immunoprecipitate and identify RNAs and protein components by RIP-Seq and mass spectrometry. This reveals the composition of the SL1 snRNP and identifies associations with spliceosome components PRP-8 and PRP-19. Significantly, we identify a novel, nematode-specific protein required for SL1 trans-splicing, which we designate SNA-3. SNA-3 is an essential, nuclear protein with three NADAR domains whose function is unknown. Mutation of key residues in NADAR domains inactivates the protein, indicating that domain function is required for activity. SNA-3 interacts with the CBC-ARS2 complex and other factors involved in RNA metabolism, including SUT-1 protein, through RNA or protein-mediated contacts revealed by yeast two-hybrid assays, localisation studies and immunoprecipitations. Our data are compatible with a role for SNA-3 in coordinating trans-splicing with target pre-mRNA transcription or in the processing of the Y-branch product of the trans-splicing reaction.
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Affiliation(s)
- Rotimi Yemi Fasimoye
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Rosie Elizabeth Barker Spencer
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Eva Soto-Martin
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Peter Eijlers
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Haitem Elmassoudi
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Sarah Brivio
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Carolina Mangana
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Viktorija Sabele
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Radoslava Rechtorikova
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Marius Wenzel
- Centre of Genome-Enabled Biology and Medicine, University of Aberdeen, 23 St Machar Drive, Aberdeen AB24 3RY, Scotland, UK
| | - Bernadette Connolly
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Jonathan Pettitt
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Berndt Müller
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
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10
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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: 13] [Impact Index Per Article: 6.5] [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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11
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The great small organisms of developmental genetics: Caenorhabditis elegans and Drosophila melanogaster. Dev Biol 2022; 485:93-122. [PMID: 35247454 PMCID: PMC9092520 DOI: 10.1016/j.ydbio.2022.02.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/25/2022] [Accepted: 02/27/2022] [Indexed: 12/30/2022]
Abstract
Experimental embryologists working at the turn of the 19th century suggested fundamental mechanisms of development, such as localized cytoplasmic determinants and tissue induction. However, the molecular basis underlying these processes proved intractable for a long time, despite concerted efforts in many developmental systems to isolate factors with a biological role. That road block was overcome by combining developmental biology with genetics. This powerful approach used unbiased genome-wide screens to isolate mutants with developmental defects and to thereby identify genes encoding key determinants and regulatory pathways that govern development. Two small invertebrates were the pioneers: the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans. Their modes of development differ in many ways, but the two together led the way to unraveling the molecular mechanisms of many fundamental developmental processes. The discovery of the grand homologies between key players in development throughout the animal kingdom underscored the usefulness of studying these small invertebrate models for animal development and even human disease. We describe developmental genetics in Drosophila and C. elegans up to the rise of genomics at the beginning of the 21st Century. Finally, we discuss themes that emerge from the histories of such distinct organisms and prospects of this approach for the future.
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12
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Unno T, Takatsuka H, Ohnishi Y, Ito M, Kubota Y. A class I histone deacetylase HDA-2 is essential for embryonic development and size regulation of fertilized eggs in Caenorhabditis elegans. Genes Genomics 2021; 44:343-357. [PMID: 34843089 DOI: 10.1007/s13258-021-01195-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 11/21/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND Caenorhabditis elegans encodes three class I histone deacetylases (HDACs), HDA-1, HDA-2, and HDA-3. Although HDA-1 is known to be involved in embryogenesis, the regulatory roles of HDA-2 and HDA-3 in embryonic development remain unexplored. OBJECTIVE To elucidate the functional roles of the three class I HDACs in C. elegans embryonic development. METHODS The roles of Class I HDACs, HDA-1, HDA-2, and HDA-3 in Caenorhabditis elegans during embryogenesis were investigated through the analysis of embryonic lethality via gene knockdown or deletion mutants. Additionally, the size of these knockdown and mutant eggs was observed using a differential interference contrast microscope. Finally, expression pattern and tissue-specific role of hda-2 and transcriptome of the hda-2 mutant were analyzed. RESULTS Here, we report that HDA-1 and HDA-2, but not HDA-3, play essential roles in Caenorhabditis elegans embryonic development. Our observations of the fertilized egg size variance demonstrated that HDA-2 is involved in regulating the size of fertilized eggs. Combined analysis of expression patterns and sheath cell-specific rescue experiments indicated that the transgenerational role of HDA-2 is involved in the viability of embryonic development and fertilized egg size regulation. Furthermore, transcriptome analysis of hda-2 mutant embryos implies that HDA-2 is involved in epigenetic regulation of embryonic biological processes by downregulating and upregulating the gene expression. CONCLUSION Our finding suggests that HDA-2 regulates the embryonic development in Caenorhabditis elegans by controling a specific subset of genes, and this function might be mediated by transgenerational epigenetic effect.
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Affiliation(s)
- Takuma Unno
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan
| | - Hisashi Takatsuka
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan
| | - Yuto Ohnishi
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan
| | - Masahiro Ito
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.,Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan
| | - Yukihiko Kubota
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.
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13
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Pastore B, Hertz HL, Price IF, Tang W. pre-piRNA trimming and 2'-O-methylation protect piRNAs from 3' tailing and degradation in C. elegans. Cell Rep 2021; 36:109640. [PMID: 34469728 PMCID: PMC8459939 DOI: 10.1016/j.celrep.2021.109640] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 06/24/2021] [Accepted: 08/10/2021] [Indexed: 11/30/2022] Open
Abstract
The Piwi-interacting RNA (piRNA) pathway suppresses transposable elements and promotes fertility in diverse organisms. Maturation of piRNAs involves pre-piRNA trimming followed by 2'-O-methylation at their 3' termini. Here, we report that the 3' termini of Caenorhabditis elegans piRNAs are subject to nontemplated nucleotide addition, and piRNAs with 3' addition exhibit extensive base-pairing interaction with their target RNAs. Animals deficient for PARN-1 (pre-piRNA trimmer) and HENN-1 (2'-O-methyltransferase) accumulate piRNAs with 3' nontemplated nucleotides. In henn-1 mutants, piRNAs are shortened prior to 3' addition, whereas long isoforms of untrimmed piRNAs are preferentially modified in parn-1 mutant animals. Loss of either PARN-1 or HENN-1 results in modest reduction in steady-state levels of piRNAs. Deletion of both enzymes leads to depletion of piRNAs, desilenced piRNA targets, and impaired fecundity. Together, our findings suggest that pre-piRNA trimming and 2'-O-methylation act collaboratively to protect piRNAs from tailing and degradation.
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Affiliation(s)
- Benjamin Pastore
- Department of Biological Chemistry and Pharmacology, Columbus, OH 43210, USA; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA; Ohio State Biochemistry Program, Columbus, OH 43210, USA
| | - Hannah L Hertz
- Department of Biological Chemistry and Pharmacology, Columbus, OH 43210, USA; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Ian F Price
- Department of Biological Chemistry and Pharmacology, Columbus, OH 43210, USA; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA; Ohio State Biochemistry Program, Columbus, OH 43210, USA
| | - Wen Tang
- Department of Biological Chemistry and Pharmacology, Columbus, OH 43210, USA; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.
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14
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Vong YH, Sivashanmugam L, Leech R, Zaucker A, Jones A, Sampath K. The RNA-binding protein Igf2bp3 is critical for embryonic and germline development in zebrafish. PLoS Genet 2021; 17:e1009667. [PMID: 34214072 PMCID: PMC8282044 DOI: 10.1371/journal.pgen.1009667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 07/15/2021] [Accepted: 06/15/2021] [Indexed: 11/18/2022] Open
Abstract
The ability to reproduce is essential in all branches of life. In metazoans, this process is initiated by formation of the germline, a group of cells that are destined to form the future gonads, the tissue that will produce the gametes. The molecular mechanisms underlying germline formation differs between species. In zebrafish, development of the germline is dependent on the specification, migration and proliferation of progenitors called the primordial germ cells (PGCs). PGC specification is dependent on a maternally provided cytoplasmic complex of ribonucleoproteins (RNPs), the germplasm. Here, we show that the conserved RNA-binding protein (RBP), Igf2bp3, has an essential role during early embryonic development and germline development. Loss of Igf2bp3 leads to an expanded yolk syncytial layer (YSL) in early embryos, reduced germline RNA expression, and mis-regulated germline development. We show that loss of maternal Igf2bp3 function results in translational de-regulation of a Nodal reporter during the mid-blastula transition. Furthermore, maternal igf2bp3 mutants exhibit reduced expression of germplasm transcripts, defects in chemokine guidance, abnormal PGC behavior and germ cell death. Consistently, adult igf2bp3 mutants show a strong male bias. Our findings suggest that Igf2bp3 is essential for normal embryonic and germline development, and acts as a key regulator of sexual development.
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Affiliation(s)
- Yin Ho Vong
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Lavanya Sivashanmugam
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Rebecca Leech
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Andreas Zaucker
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Alex Jones
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Karuna Sampath
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
- Centre for Early Life, University of Warwick, Coventry, United Kingdom
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, United Kingdom
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15
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Lim YW, Wen FL, Shankar P, Shibata T, Motegi F. A balance between antagonizing PAR proteins specifies the pattern of asymmetric and symmetric divisions in C. elegans embryogenesis. Cell Rep 2021; 36:109326. [PMID: 34233197 DOI: 10.1016/j.celrep.2021.109326] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 03/05/2021] [Accepted: 06/08/2021] [Indexed: 10/20/2022] Open
Abstract
Coordination between cell differentiation and proliferation during development requires the balance between asymmetric and symmetric modes of cell division. However, the cellular intrinsic cue underlying the choice between these two division modes remains elusive. Here, we show evidence in Caenorhabditis elegans that the invariable lineage of the division modes is specified by the balance between antagonizing complexes of partitioning-defective (PAR) proteins. By uncoupling unequal inheritance of PAR proteins from that of fate determinants during cell division, we demonstrate that changes in the balance between PAR-2 and PAR-6 can be sufficient to re-program the division modes from symmetric to asymmetric and vice versa in two daughter cells. The division mode adopted occurs independently of asymmetry in cytoplasmic fate determinants, cell-size asymmetry, and cell-cycle asynchrony between sister cells. We propose that the balance between PAR proteins represents an intrinsic self-organizing cue for the specification of the two division modes during development.
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Affiliation(s)
- Yen Wei Lim
- Temasek Life-sciences Laboratory, Singapore 117604, Singapore; Department of Biological Sciences, National University of Singapore, Singapore 117583, Singapore
| | - Fu-Lai Wen
- RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Prabhat Shankar
- RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Tatsuo Shibata
- RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan.
| | - Fumio Motegi
- Temasek Life-sciences Laboratory, Singapore 117604, Singapore; Department of Biological Sciences, National University of Singapore, Singapore 117583, Singapore; Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore; Institute for Genetic Medicine, Hokkaido University, Sapporo 060-0815, Japan.
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16
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Carpenter BS, Lee TW, Plott CF, Rodriguez JD, Brockett JS, Myrick DA, Katz DJ. Caenorhabditis elegans establishes germline versus soma by balancing inherited histone methylation. Development 2021; 148:dev.196600. [PMID: 33462111 DOI: 10.1242/dev.196600] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 01/04/2021] [Indexed: 12/12/2022]
Abstract
Formation of a zygote is coupled with extensive epigenetic reprogramming to enable appropriate inheritance of histone methylation and prevent developmental delays. In Caenorhabditis elegans, this reprogramming is mediated by the H3K4me2 demethylase SPR-5 and the H3K9 methyltransferase, MET-2. In contrast, the H3K36 methyltransferase MES-4 maintains H3K36me2/3 at germline genes between generations to facilitate re-establishment of the germline. To determine whether the MES-4 germline inheritance pathway antagonizes spr-5; met-2 reprogramming, we examined the interaction between these two pathways. We found that the developmental delay of spr-5; met-2 mutant progeny is associated with ectopic H3K36me3 and the ectopic expression of MES-4-targeted germline genes in somatic tissues. Furthermore, the developmental delay is dependent upon MES-4 and the H3K4 methyltransferase, SET-2. We propose that MES-4 prevents crucial germline genes from being repressed by antagonizing maternal spr-5; met-2 reprogramming. Thus, the balance of inherited histone modifications is necessary to distinguish germline versus soma and prevent developmental delay.This article has an associated 'The people behind the papers' interview.
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Affiliation(s)
- Brandon S Carpenter
- Department of Cell Biology, Emory University School of Medicine, Atlanta GA 30322, USA
| | - Teresa W Lee
- Department of Cell Biology, Emory University School of Medicine, Atlanta GA 30322, USA
| | - Caroline F Plott
- Johns Hopkins University School of Medicine, Baltimore MD 21205, USA
| | - Juan D Rodriguez
- Department of Cell Biology, Emory University School of Medicine, Atlanta GA 30322, USA
| | - Jovan S Brockett
- Department of Biology, Oglethorpe University, Atlanta GA 30319, USA
| | - Dexter A Myrick
- Department of Cell Biology, Emory University School of Medicine, Atlanta GA 30322, USA
| | - David J Katz
- Department of Cell Biology, Emory University School of Medicine, Atlanta GA 30322, USA
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17
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Dodson AE, Kennedy S. Phase Separation in Germ Cells and Development. Dev Cell 2020; 55:4-17. [PMID: 33007213 DOI: 10.1016/j.devcel.2020.09.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/28/2020] [Accepted: 09/05/2020] [Indexed: 12/20/2022]
Abstract
The animal germline is an immortal cell lineage that gives rise to eggs and/or sperm each generation. Fusion of an egg and sperm, or fertilization, sets off a cascade of developmental events capable of producing an array of different cell types and body plans. How germ cells develop, function, and eventually give rise to entirely new organisms is an important question in biology. A growing body of evidence suggests that phase separation events likely play a significant and multifaceted role in germ cells and development. Here, we discuss the organization, dynamics, and potential functions of phase-separated compartments in germ cells and examine the various ways in which phase separation might contribute to the development of multicellular organisms.
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Affiliation(s)
- Anne E Dodson
- Department of Genetics, Blavatnik Institute at Harvard Medical School, Boston, MA 02115, USA.
| | - Scott Kennedy
- Department of Genetics, Blavatnik Institute at Harvard Medical School, Boston, MA 02115, USA
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18
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Défachelles L, Russo AE, Nelson CR, Bhalla N. The conserved AAA-ATPase PCH-2 TRIP13 regulates spindle checkpoint strength. Mol Biol Cell 2020; 31:2219-2233. [PMID: 32697629 PMCID: PMC7550697 DOI: 10.1091/mbc.e20-05-0310] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Spindle checkpoint strength is dictated by the number of unattached kinetochores, cell volume, and cell fate. We show that the conserved AAA-ATPase PCH-2/TRIP13, which remodels the checkpoint effector Mad2 from an active conformation to an inactive one, controls checkpoint strength in Caenorhabditis elegans. Having previously established that this function is required for spindle checkpoint activation, we demonstrate that in cells genetically manipulated to decrease in cell volume, PCH-2 is no longer required for the spindle checkpoint or recruitment of Mad2 at unattached kinetochores. This role is not limited to large cells: the stronger checkpoint in germline precursor cells also depends on PCH-2. PCH-2 is enriched in germline precursor cells, and this enrichment relies on conserved factors that induce asymmetry in the early embryo. Finally, the stronger checkpoint in germline precursor cells is regulated by CMT-1, the ortholog of p31comet, which is required for both PCH-2′s localization to unattached kinetochores and its enrichment in germline precursor cells. Thus, PCH-2, likely by regulating the availability of inactive Mad2 at and near unattached kinetochores, governs checkpoint strength. This requirement may be particularly relevant in oocytes and early embryos enlarged for developmental competence, cells that divide in syncytial tissues, and immortal germline cells.
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Affiliation(s)
- Lénaïg Défachelles
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Anna E Russo
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Christian R Nelson
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Needhi Bhalla
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
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19
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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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20
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Wu E, Vastenhouw NL. From mother to embryo: A molecular perspective on zygotic genome activation. Curr Top Dev Biol 2020; 140:209-254. [PMID: 32591075 DOI: 10.1016/bs.ctdb.2020.02.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In animals, the early embryo is mostly transcriptionally silent and development is fueled by maternally supplied mRNAs and proteins. These maternal products are important not only for survival, but also to gear up the zygote's genome for activation. Over the last three decades, research with different model organisms and experimental approaches has identified molecular factors and proposed mechanisms for how the embryo transitions from being transcriptionally silent to transcriptionally competent. In this chapter, we discuss the molecular players that shape the molecular landscape of ZGA and provide insights into their mode of action in activating the transcription program in the developing embryo.
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Affiliation(s)
- Edlyn Wu
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Nadine L Vastenhouw
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
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21
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Goldstein B, Nance J. Caenorhabditis elegans Gastrulation: A Model for Understanding How Cells Polarize, Change Shape, and Journey Toward the Center of an Embryo. Genetics 2020; 214:265-277. [PMID: 32029580 PMCID: PMC7017025 DOI: 10.1534/genetics.119.300240] [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: 11/01/2019] [Accepted: 12/02/2019] [Indexed: 11/18/2022] Open
Abstract
Gastrulation is fundamental to the development of multicellular animals. Along with neurulation, gastrulation is one of the major processes of morphogenesis in which cells or whole tissues move from the surface of an embryo to its interior. Cell internalization mechanisms that have been discovered to date in Caenorhabditis elegans gastrulation bear some similarity to internalization mechanisms of other systems including Drosophila, Xenopus, and mouse, suggesting that ancient and conserved mechanisms internalize cells in diverse organisms. C. elegans gastrulation occurs at an early stage, beginning when the embryo is composed of just 26 cells, suggesting some promise for connecting the rich array of developmental mechanisms that establish polarity and pattern in embryos to the force-producing mechanisms that change cell shapes and move cells interiorly. Here, we review our current understanding of C. elegans gastrulation mechanisms. We address how cells determine which direction is the interior and polarize with respect to that direction, how cells change shape by apical constriction and internalize, and how the embryo specifies which cells will internalize and when. We summarize future prospects for using this system to discover some of the general principles by which animal cells change shape and internalize during development.
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Affiliation(s)
- Bob Goldstein
- Department of Biology and
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, North Carolina 27599 and
| | - Jeremy Nance
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine and
- Department of Cell Biology, New York University School of Medicine, New York 10016
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22
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Hansel, Gretel, and the Consequences of Failing to Remove Histone Methylation Breadcrumbs. Trends Genet 2020; 36:160-176. [PMID: 32007289 PMCID: PMC10047806 DOI: 10.1016/j.tig.2019.12.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/20/2019] [Accepted: 12/06/2019] [Indexed: 02/07/2023]
Abstract
Like breadcrumbs in the forest, cotranscriptionally acquired histone methylation acts as a memory of prior transcription. Because it can be retained through cell divisions, transcriptional memory allows cells to coordinate complex transcriptional programs during development. However, if not reprogrammed properly during cell fate transitions, it can also disrupt cellular identity. In this review, we discuss the consequences of failure to reprogram histone methylation during three crucial epigenetic reprogramming windows: maternal reprogramming at fertilization, embryonic stem cell (ESC) differentiation, and the continuous maintenance of cell identity in differentiated cells. In addition, we discuss how following the wrong breadcrumb trail of transcriptional memory provides a framework for understanding how heterozygous loss-of-function mutations in histone-modifying enzymes may cause severe neurodevelopmental disorders.
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23
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Rothman J, Jarriault S. Developmental Plasticity and Cellular Reprogramming in Caenorhabditis elegans. Genetics 2019; 213:723-757. [PMID: 31685551 PMCID: PMC6827377 DOI: 10.1534/genetics.119.302333] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 07/25/2019] [Indexed: 12/28/2022] Open
Abstract
While Caenorhabditis elegans was originally regarded as a model for investigating determinate developmental programs, landmark studies have subsequently shown that the largely invariant pattern of development in the animal does not reflect irreversibility in rigidly fixed cell fates. Rather, cells at all stages of development, in both the soma and germline, have been shown to be capable of changing their fates through mutation or forced expression of fate-determining factors, as well as during the normal course of development. In this chapter, we review the basis for natural and induced cellular plasticity in C. elegans We describe the events that progressively restrict cellular differentiation during embryogenesis, starting with the multipotency-to-commitment transition (MCT) and subsequently through postembryonic development of the animal, and consider the range of molecular processes, including transcriptional and translational control systems, that contribute to cellular plasticity. These findings in the worm are discussed in the context of both classical and recent studies of cellular plasticity in vertebrate systems.
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Affiliation(s)
- Joel Rothman
- Department of MCD Biology and Neuroscience Research Institute, University of California, Santa Barbara, California 93111, and
| | - Sophie Jarriault
- IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Department of Development and Stem Cells, CNRS UMR7104, Inserm U1258, Université de Strasbourg, 67404 Illkirch CU Strasbourg, France
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24
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Sun X, Chen Y, Yu H, Machan JT, Alladin A, Ramirez J, Taliano R, Hart J, Chen Q, Terek RM. Anti-miRNA Oligonucleotide Therapy for Chondrosarcoma. Mol Cancer Ther 2019; 18:2021-2029. [PMID: 31341031 DOI: 10.1158/1535-7163.mct-18-1020] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 05/10/2019] [Accepted: 07/19/2019] [Indexed: 02/03/2023]
Abstract
Chondrosarcoma is a highly aggressive primary malignant bone tumor mostly occurring in adults. There are no effective systemic treatments, and patients with this disease have poor survival. miR-181a is an oncomiR that is overexpressed in high-grade chondrosarcoma and promotes tumor progression. Regulator of G-protein signaling 16 (RGS16) is a target of miR-181a. Inhibition of RGS16 expression by miR-181a enhances CXC chemokine receptor 4 signaling, which in turn increases MMP1 and VEGF expression, angiogenesis, and metastasis. Here, we report the results of systemic treatment with anti-miRNA oligonucleotides (AMO) directed against miR-181a utilizing a nanopiece delivery platform (NPs). NPs were combined with a molecular beacon or anti-miR-181a oligonucleotides and are shown to transfect chondrosarcoma cells in vitro and in vivo Intratumoral injection and systemic delivery had similar effects on miR-181a expression in nude mice bearing chondrosarcoma xenografts. Systemic delivery of NPs carrying anti-miR-181a also restored RGS16 expression, decreased expression of VEGF and MMP1, MMP activity, and tumor volume by 32% at day 38, and prolonged survival from 23% to 45%. In conclusion, these data support that systemic delivery of AMO shows promise for chondrosarcoma treatment.
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Affiliation(s)
- Xiaojuan Sun
- Department of Orthopaedics, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - Yupeng Chen
- Department of Orthopaedics, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
- Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut
| | - Hongchuan Yu
- Department of Orthopaedics, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - Jason T Machan
- Department of Orthopaedics, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
- Lifespan Biostatistics Core, Lifespan Hospital System, Providence, Rhode Island
- Department of Surgery, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - Ashna Alladin
- Department of Orthopaedics, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - Jose Ramirez
- Department of Orthopaedics, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - Ross Taliano
- Department of Pathology, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - Jesse Hart
- Department of Pathology, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - Qian Chen
- Department of Orthopaedics, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - Richard M Terek
- Department of Orthopaedics, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island.
- Providence Veterans Administration Medical Center, Providence, Rhode Island
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25
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Vastenhouw NL, Cao WX, Lipshitz HD. The maternal-to-zygotic transition revisited. Development 2019; 146:146/11/dev161471. [PMID: 31189646 DOI: 10.1242/dev.161471] [Citation(s) in RCA: 198] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The development of animal embryos is initially directed by maternal gene products. Then, during the maternal-to-zygotic transition (MZT), developmental control is handed to the zygotic genome. Extensive research in both vertebrate and invertebrate model organisms has revealed that the MZT can be subdivided into two phases, during which very different modes of gene regulation are implemented: initially, regulation is exclusively post-transcriptional and post-translational, following which gradual activation of the zygotic genome leads to predominance of transcriptional regulation. These changes in the gene expression program of embryos are precisely controlled and highly interconnected. Here, we review current understanding of the mechanisms that underlie handover of developmental control during the MZT.
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Affiliation(s)
- Nadine L Vastenhouw
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, 01307 Dresden, Germany
| | - Wen Xi Cao
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, Ontario M5G 1M1, Canada
| | - Howard D Lipshitz
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, Ontario M5G 1M1, Canada
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26
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Asaoka M, Hanyu-Nakamura K, Nakamura A, Kobayashi S. Maternal Nanos inhibits Importin-α2/Pendulin-dependent nuclear import to prevent somatic gene expression in the Drosophila germline. PLoS Genet 2019; 15:e1008090. [PMID: 31091233 PMCID: PMC6519790 DOI: 10.1371/journal.pgen.1008090] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 03/13/2019] [Indexed: 01/15/2023] Open
Abstract
Repression of somatic gene expression in germline progenitors is one of the critical mechanisms involved in establishing the germ/soma dichotomy. In Drosophila, the maternal Nanos (Nos) and Polar granule component (Pgc) proteins are required for repression of somatic gene expression in the primordial germ cells, or pole cells. Pgc suppresses RNA polymerase II-dependent global transcription in pole cells, but it remains unclear how Nos represses somatic gene expression. Here, we show that Nos represses somatic gene expression by inhibiting translation of maternal importin-α2 (impα2) mRNA. Mis-expression of Impα2 caused aberrant nuclear import of a transcriptional activator, Ftz-F1, which in turn activated a somatic gene, fushi tarazu (ftz), in pole cells when Pgc-dependent transcriptional repression was impaired. Because ftz expression was not fully activated in pole cells in the absence of either Nos or Pgc, we propose that Nos-dependent repression of nuclear import of transcriptional activator(s) and Pgc-dependent suppression of global transcription act as a 'double-lock' mechanism to inhibit somatic gene expression in germline progenitors.
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Affiliation(s)
- Miho Asaoka
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Kazuko Hanyu-Nakamura
- Department of Germline Development, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan
| | - Akira Nakamura
- Department of Germline Development, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan
- Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Satoru Kobayashi
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki, Japan
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
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27
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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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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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PIE-1 Translation in the Germline Lineage Contributes to PIE-1 Asymmetry in the Early Caenorhabditis elegans Embryo. G3-GENES GENOMES GENETICS 2018; 8:3791-3801. [PMID: 30279189 PMCID: PMC6288838 DOI: 10.1534/g3.118.200744] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In the C. elegans embryo, the germline lineage is established through successive asymmetric cell divisions that each generate a somatic and a germline daughter cell. PIE-1 is an essential maternal factor that is enriched in embryonic germline cells and is required for germline specification. We estimated the absolute concentration of PIE-1::GFP in germline cells and find that PIE-1::GFP concentration increases by roughly 4.5 fold, from 92 nM to 424 nM, between the 1 and 4-cell stages. Previous studies have shown that the preferential inheritance of PIE-1 by germline daughter cells and the degradation of PIE-1 in somatic cells are important for PIE-1 enrichment in germline cells. In this study, we provide evidence that the preferential translation of maternal PIE-1::GFP transcripts in the germline also contributes to PIE-1::GFP enrichment. Through an RNAi screen, we identified Y14 and MAG-1 (Drosophila tsunagi and mago nashi) as regulators of embryonic PIE-1::GFP levels. We show that Y14 and MAG-1 do not regulate PIE-1 degradation, segregation or synthesis in the early embryo, but do regulate the concentration of maternally-deposited PIE-1::GFP. Taken together, or findings point to an important role for translational control in the regulation of PIE-1 levels in the germline lineage.
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30
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Spatiotemporal m(i)RNA Architecture and 3' UTR Regulation in the C. elegans Germline. Dev Cell 2018; 47:785-800.e8. [PMID: 30416012 DOI: 10.1016/j.devcel.2018.10.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/31/2018] [Accepted: 10/04/2018] [Indexed: 12/26/2022]
Abstract
In animal germlines, regulation of cell proliferation and differentiation is particularly important but poorly understood. Here, using a cryo-cut approach, we mapped RNA expression along the Caenorhabditis elegans germline and, using mutants, dissected gene regulatory mechanisms that control spatiotemporal expression. We detected, at near single-cell resolution, >10,000 mRNAs, >300 miRNAs, and numerous unannotated miRNAs. Most RNAs were organized in distinct spatial patterns. Germline-specific miRNAs and their targets were co-localized. Moreover, we observed differential 3' UTR isoform usage for hundreds of mRNAs. In tumorous gld-2 gld-1 mutants, gene expression was strongly perturbed. In particular, differential 3' UTR usage was significantly impaired. We propose that PIE-1, a transcriptional repressor, functions to maintain spatial gene expression. Our data also suggest that cpsf-4 and fipp-1 control differential 3' UTR usage for hundreds of genes. Finally, we constructed a "virtual gonad" enabling "virtual in situ hybridizations" and access to all data (https://shiny.mdc-berlin.de/spacegerm/).
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31
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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 DOI: 10.1080/10409238.2018.1506733] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [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)
- Lyubov A Lebedeva
- a Institute of Gene Biology , Russian Academy of Sciences , Moscow , Russia
| | - Konstantin V Yakovlev
- a Institute of Gene Biology , Russian Academy of Sciences , Moscow , Russia.,b Laboratory of Cytotechnology, National Scientific Center of Marine Biology, Far Eastern Branch , Russian Academy of Sciences , Vladivostok , Russia
| | - Eugene N Kozlov
- a Institute of Gene Biology , Russian Academy of Sciences , Moscow , Russia
| | - Paul Schedl
- a Institute of Gene Biology , Russian Academy of Sciences , Moscow , Russia.,c Department of Molecular Biology , Princeton University , Princeton , USA
| | - Girish Deshpande
- c Department of Molecular Biology , Princeton University , Princeton , USA
| | - Yulii V Shidlovskii
- a Institute of Gene Biology , Russian Academy of Sciences , Moscow , Russia.,d Department of Biology and General Genetics, I.M. Sechenov First Moscow State Medical University , Moscow , Russia
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32
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Treen N, Heist T, Wang W, Levine M. Depletion of Maternal Cyclin B3 Contributes to Zygotic Genome Activation in the Ciona Embryo. Curr Biol 2018; 28:1150-1156.e4. [PMID: 29576477 PMCID: PMC5996753 DOI: 10.1016/j.cub.2018.02.046] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 12/18/2017] [Accepted: 02/16/2018] [Indexed: 10/17/2022]
Abstract
Most animal embryos display a delay in the activation of zygotic transcription during early embryogenesis [1]. This process is thought to help coordinate rapid increases in cell number during early development [2]. The timing of zygotic genome activation (ZGA) during the maternal-to-zygotic transition (MZT) remains uncertain despite extensive efforts. We explore ZGA in the simple protovertebrate, Ciona intestinalis. Single-cell RNA sequencing (RNA-seq) assays identified Cyclin B3 (Ccnb3) as a putative mediator of ZGA. Maternal Ccnb3 transcripts rapidly diminish in abundance during the onset of zygotic transcription at the 8-cell and 16-cell stages. Disruption of Ccnb3 activity results in precocious activation of zygotic transcription, while overexpression abolishes normal activation. These observations suggest that the depletion of maternal Cyclin B3 products is a critical component of the MZT and ZGA. We discuss evidence that this mechanism might play a conserved role in the MZT of other metazoans, including mice and humans.
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Affiliation(s)
- Nicholas Treen
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA.
| | - Tyler Heist
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Wei Wang
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Michael Levine
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
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33
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Fassnacht C, Tocchini C, Kumari P, Gaidatzis D, Stadler MB, Ciosk R. The CSR-1 endogenous RNAi pathway ensures accurate transcriptional reprogramming during the oocyte-to-embryo transition in Caenorhabditis elegans. PLoS Genet 2018; 14:e1007252. [PMID: 29579041 PMCID: PMC5886687 DOI: 10.1371/journal.pgen.1007252] [Citation(s) in RCA: 13] [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: 09/06/2017] [Revised: 04/05/2018] [Accepted: 02/13/2018] [Indexed: 12/30/2022] Open
Abstract
Endogenous RNAi (endoRNAi) is a conserved mechanism for fine-tuning gene expression. In the nematode Caenorhabditis elegans, several endoRNAi pathways are required for the successful development of reproductive cells. The CSR-1 endoRNAi pathway promotes germ cell development, primarily by facilitating the expression of germline genes. In this study, we report a novel function for the CSR-1 pathway in preventing premature activation of embryonic transcription in the developing oocytes, which is accompanied by a general Pol II activation. This CSR-1 function requires its RNase activity, suggesting that, by controlling the levels of maternal mRNAs, CSR-1-dependent endoRNAi contributes to an orderly reprogramming of transcription during the oocyte-to-embryo transition. During the oocyte-to-embryo transition, the control of development is transferred from the mother to the embryo. A key event during this transition is the transcriptional activation of the embryonic genome, which is tightly controlled. Here, by using the nematode C. elegans, we uncover a role for endogenous RNA interference in this process. We demonstrate that a specific endoRNAi pathway, employing the Argonaute protein CSR-1, functions as a break on gene-specific, and potentially global, activation of embryonic transcription in the developing oocytes. Our findings reveal a new layer of control over the transcriptional reprogramming during the oocyte-to-embryo transition, raising questions about its potential conservation in mammalian development.
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Affiliation(s)
- Christina Fassnacht
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Cristina Tocchini
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Pooja Kumari
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Dimos Gaidatzis
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Michael B. Stadler
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Rafal Ciosk
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
- * E-mail: ,
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34
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McManus CE, Reinke V. The Germline-Specific Factor OEF-1 Facilitates Coordinated Progression Through Germ Cell Development in Caenorhabditis elegans. Genetics 2018; 208:549-563. [PMID: 29167199 PMCID: PMC5788521 DOI: 10.1534/genetics.117.1123] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 11/19/2017] [Indexed: 11/18/2022] Open
Abstract
The purpose of germ cells is to ensure the faithful transmission of genetic material to the next generation. To develop into mature gametes, germ cells must pass through cell cycle checkpoints while maintaining totipotency and genomic integrity. How germ cells coordinate developmental events while simultaneously protecting their unique fate is not well understood. Here, we characterize a novel nuclear protein, Oocyte-Excluded Factor-1 (OEF-1), with highly specific germline expression in Caenorhabditis elegans OEF-1 is initially detected early in embryogenesis and is expressed in the nuclei of all germ cells during larval stages. In adults, OEF-1 expression abruptly decreases just prior to oocyte differentiation. In oef-1 mutants, the developmental progression of germ cells is accelerated, resulting in subtle defects at multiple stages of germ cell development. Lastly, OEF-1 is primarily associated with the bodies of germline-expressed genes, and as such is excluded from the X chromosome. We hypothesize that OEF-1 may regulate the rate of progression through germ cell development, providing insight into how these critical maturation events are coordinated.
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Affiliation(s)
- Catherine E McManus
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Valerie Reinke
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06520
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35
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Lee CYS, Lu T, Seydoux G. Nanos promotes epigenetic reprograming of the germline by down-regulation of the THAP transcription factor LIN-15B. eLife 2017; 6:30201. [PMID: 29111977 PMCID: PMC5734877 DOI: 10.7554/elife.30201] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 11/06/2017] [Indexed: 12/15/2022] Open
Abstract
Nanos RNA-binding proteins are required for germline development in metazoans, but the underlying mechanisms remain poorly understood. We have profiled the transcriptome of primordial germ cells (PGCs) lacking the nanos homologs nos-1 and nos-2 in C. elegans. nos-1nos-2 PGCs fail to silence hundreds of transcripts normally expressed in oocytes. We find that this misregulation is due to both delayed turnover of maternal transcripts and inappropriate transcriptional activation. The latter appears to be an indirect consequence of delayed turnover of the maternally-inherited transcription factor LIN-15B, a synMuvB class transcription factor known to antagonize PRC2 activity. PRC2 is required for chromatin reprogramming in the germline, and the transcriptome of PGCs lacking PRC2 resembles that of nos-1nos-2 PGCs. Loss of maternal LIN-15B restores fertility to nos-1nos-2 mutants. These findings suggest that Nanos promotes germ cell fate by downregulating maternal RNAs and proteins that would otherwise interfere with PRC2-dependent reprogramming of PGC chromatin.
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Affiliation(s)
- Chih-Yung Sean Lee
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Tu Lu
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Geraldine Seydoux
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
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36
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Fickentscher R, Weiss M. Physical determinants of asymmetric cell divisions in the early development of Caenorhabditis elegans. Sci Rep 2017; 7:9369. [PMID: 28839200 PMCID: PMC5571195 DOI: 10.1038/s41598-017-09690-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 07/25/2017] [Indexed: 01/06/2023] Open
Abstract
Asymmetric cell divisions are of fundamental importance for the development of multicellular organisms, e.g. for the generation of founder cells. Prime examples are asymmetric cell divisions in germline precursors during the early embryogenesis of the transparent roundworm Caenorhabditis elegans, one of the major developmental model organisms. However, due to a lack of quantitative data it has remained unclear how frequent unequal daughter cell sizes emerge in the worm’s early embryogenesis, and whether these originate from sterical or biochemical cues. Using quantitative light-sheet microscopy, we have found that about 40% of all cell divisions in C. elegans until gastrulation generate daughter cells with significantly different volumes. Removing the embryo’s rigid eggshell revealed asymmetric divisions in somatic cells to be primarily induced by steric effects. Division asymmetries in the germline remained unaltered and were correctly reproduced by a model based on a cell-size independent, eccentric displacement of the metaphase plate. Our data suggest that asymmetric cell divisions, imposed by physical determinants, are essential for establishing important cell-cell interactions that eventually fuel a successful embryogenesis.
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Affiliation(s)
- Rolf Fickentscher
- Experimental Physics I, University of Bayreuth, D-95440, Bayreuth, Germany
| | - Matthias Weiss
- Experimental Physics I, University of Bayreuth, D-95440, Bayreuth, Germany.
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37
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Reduction in chromosome mobility accompanies nuclear organization during early embryogenesis in Caenorhabditis elegans. Sci Rep 2017. [PMID: 28623274 PMCID: PMC5473868 DOI: 10.1038/s41598-017-03483-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In differentiated cells, chromosomes are packed inside the cell nucleus in an organised fashion. In contrast, little is known about how chromosomes are packed in undifferentiated cells and how nuclear organization changes during development. To assess changes in nuclear organization during the earliest stages of development, we quantified the mobility of a pair of homologous chromosomal loci in the interphase nuclei of Caenorhabditis elegans embryos. The distribution of distances between homologous loci was consistent with a random distribution up to the 8-cell stage but not at later stages. The mobility of the loci was significantly reduced from the 2-cell to the 48-cell stage. Nuclear foci corresponding to epigenetic marks as well as heterochromatin and the nucleolus also appeared around the 8-cell stage. We propose that the earliest global transformation in nuclear organization occurs at the 8-cell stage during C. elegans embryogenesis.
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38
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Robertson SM, Medina J, Oldenbroek M, Lin R. Reciprocal signaling by Wnt and Notch specifies a muscle precursor in the C. elegans embryo. Development 2017; 144:419-429. [PMID: 28049659 DOI: 10.1242/dev.145391] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 12/12/2016] [Indexed: 11/20/2022]
Abstract
The MS blastomere produces one-third of the body wall muscles (BWMs) in the C. elegans embryo. MS-derived BWMs require two distinct cell-cell interactions, the first inhibitory and the second, two cell cycles later, required to overcome this inhibition. The inductive interaction is not required if the inhibitory signal is absent. Although the Notch receptor GLP-1 was implicated in both interactions, the molecular nature of the two signals was unknown. We now show that zygotically expressed MOM-2 (Wnt) is responsible for both interactions. Both the inhibitory and the activating interactions require precise spatiotemporal expression of zygotic MOM-2, which is dependent upon two distinct Notch signals. In a Notch mutant defective only in the inductive interaction, MS-derived BWMs can be restored by preventing zygotic MOM-2 expression, which removes the inhibitory signal. Our results suggest that the inhibitory interaction ensures the differential lineage specification of MS and its sister blastomere, whereas the inductive interaction promotes the expression of muscle-specifying genes by modulating TCF and β-catenin levels. These results highlight the complexity of cell fate specification by cell-cell interactions in a rapidly dividing embryo.
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Affiliation(s)
- Scott M Robertson
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jessica Medina
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Marieke Oldenbroek
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Rueyling Lin
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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39
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Pushpa K, Kumar GA, Subramaniam K. Translational Control of Germ Cell Decisions. Results Probl Cell Differ 2017; 59:175-200. [PMID: 28247049 DOI: 10.1007/978-3-319-44820-6_6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Germline poses unique challenges to gene expression control at the transcriptional level. While the embryonic germline maintains a global hold on new mRNA transcription, the female adult germline produces transcripts that are not translated into proteins until embryogenesis of subsequent generation. As a consequence, translational control plays a central role in governing various germ cell decisions including the formation of primordial germ cells, self-renewal/differentiation decisions in the adult germline, onset of gametogenesis and oocyte maturation. Mechanistically, several common themes such as asymmetric localization of mRNAs, conserved RNA-binding proteins that control translation by 3' UTR binding, translational activation by the cytoplasmic elongation of the polyA tail and the assembly of mRNA-protein complexes called mRNPs have emerged from the studies on Caenorhabditis elegans, Xenopus and Drosophila. How mRNPs assemble, what influences their dynamics, and how a particular 3' UTR-binding protein turns on the translation of certain mRNAs while turning off other mRNAs at the same time and space are key challenges for future work.
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Affiliation(s)
- Kumari Pushpa
- Regional Centre for Biotechnology, Faridabad, Haryana, India
| | - Ganga Anil Kumar
- Indian Institute of Technology-Kanpur, Kanpur, India.,Indian Institute of Technology-Madras, Chennai, India
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40
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Feuer S, Liu X, Donjacour A, Simbulan R, Maltepe E, Rinaudo P. Common and specific transcriptional signatures in mouse embryos and adult tissues induced by in vitro procedures. Reproduction 2016; 153:REP-16-0473. [PMID: 27799627 PMCID: PMC5411347 DOI: 10.1530/rep-16-0473] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 10/26/2016] [Indexed: 12/17/2022]
Abstract
Stressful environmental exposures incurred early in development can affect postnatal metabolic health and susceptibility to non-communicable diseases in adulthood, although the molecular mechanisms by which this occurs have yet to be elucidated. Here we use a mouse model to investigate how assorted in vitro exposures restricted exclusively to the preimplantation period affect transcription both acutely in embryos and long-term in subsequent offspring adult tissues, to determine if reliable transcriptional markers of in vitro stress are present at specific developmental time points and throughout development. Each in vitro fertilization or embryo culture environment led to a specific and unique blastocyst transcriptional profile, but we identified a common 18-gene and 9-pathway signature of preimplantation embryo manipulation that was present in all in vitro embryos irrespective of culture condition or method of fertilization. This fingerprint did not persist throughout development and there was no clear transcriptional cohesion between adult IVF offspring tissues or compared to their preceding embryos, indicating a tissue-specific impact of in vitro stress on gene expression. However, the transcriptional changes present in each IVF tissue were targeted by the same upstream transcriptional regulators, which provide insight as to how acute transcriptional responses to stressful environmental exposures might be preserved throughout development to influence adult gene expression.
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Affiliation(s)
- Sky Feuer
- S Feuer, Obstetrics and Gynecology, University of California, San Francisco, San Francisco, United States
| | - Xiaowei Liu
- X Liu, Obstetrics and Gynecology, University of California, San Francisco, San Francisco, United States
| | - Annemarie Donjacour
- A Donjacour, Obstetrics and Gynecology, University of California, San Francisco, San Francisco, United States
| | - Rhodel Simbulan
- R Simbulan, Obstetrics and Gynecology, University of California, San Francisco, San Francisco, United States
| | - Emin Maltepe
- E Maltepe, Obstetrics and Gynecology, University of California, San Francisco, San Francisco, United States
| | - Paolo Rinaudo
- P Rinaudo, Obstetrics and Gynecology, University of California, San Francisco, San Francisco, 94115, United States
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41
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Kaymak E, Farley BM, Hay SA, Li C, Ho S, Hartman DJ, Ryder SP. Efficient generation of transgenic reporter strains and analysis of expression patterns in Caenorhabditis elegans using library MosSCI. Dev Dyn 2016; 245:925-36. [PMID: 27294288 PMCID: PMC4981527 DOI: 10.1002/dvdy.24426] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 05/09/2016] [Accepted: 06/03/2016] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND In C. elegans, germline development and early embryogenesis rely on posttranscriptional regulation of maternally transcribed mRNAs. In many cases, the 3' untranslated region (UTR) is sufficient to govern the expression patterns of these transcripts. Several RNA-binding proteins are required to regulate maternal mRNAs through the 3'UTR. Despite intensive efforts to map RNA-binding protein-mRNA interactions in vivo, the biological impact of most binding events remains unknown. Reporter studies using single copy integrated transgenes are essential to evaluate the functional consequences of interactions between RNA-binding proteins and their associated mRNAs. RESULTS In this report, we present an efficient method of generating reporter strains with improved throughput by using a library variant of MosSCI transgenesis. Furthermore, using RNA interference, we identify the suite of RNA-binding proteins that control the expression pattern of five different maternal mRNAs. CONCLUSIONS The results provide a generalizable and efficient strategy to assess the functional relevance of protein-RNA interactions in vivo, and reveal new regulatory connections between key RNA-binding proteins and their maternal mRNA targets. Developmental Dynamics 245:925-936, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Ebru Kaymak
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Brian M. Farley
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
| | - Samantha A. Hay
- Virginia Commonwealth University School of Medicine, VA, USA
| | - Chihua Li
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Samantha Ho
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | | | - Sean P. Ryder
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
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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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Friday AJ, Henderson MA, Morrison JK, Hoffman JL, Keiper BD. Spatial and temporal translational control of germ cell mRNAs mediated by the eIF4E isoform IFE-1. J Cell Sci 2015; 128:4487-98. [PMID: 26542024 DOI: 10.1242/jcs.172684] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 11/02/2015] [Indexed: 11/20/2022] Open
Abstract
Regulated mRNA translation is vital for germ cells to produce new proteins in the spatial and temporal patterns that drive gamete development. Translational control involves the de-repression of stored mRNAs and their recruitment by eukaryotic initiation factors (eIFs) to ribosomes. C. elegans expresses five eIF4Es (IFE-1-IFE-5); several have been shown to selectively recruit unique pools of mRNA. Individual IFE knockouts yield unique phenotypes due to inefficient translation of certain mRNAs. Here, we identified mRNAs preferentially translated through the germline-specific eIF4E isoform IFE-1. Differential polysome microarray analysis identified 77 mRNAs recruited by IFE-1. Among the IFE-1-dependent mRNAs are several required for late germ cell differentiation and maturation. Polysome association of gld-1, vab-1, vpr-1, rab-7 and rnp-3 mRNAs relies on IFE-1. Live animal imaging showed IFE-1-dependent selectivity in spatial and temporal translation of germline mRNAs. Altered MAPK activation in oocytes suggests dual roles for IFE-1, both promoting and suppressing oocyte maturation at different stages. This single eIF4E isoform exerts positive, selective translational control during germ cell differentiation.
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Affiliation(s)
- Andrew J Friday
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
| | - Melissa A Henderson
- Department of Molecular Sciences, DeBusk College of Osteopathic Medicine, Lincoln Memorial University, Harrogate, TN 37752, USA
| | - J Kaitlin Morrison
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
| | - Jenna L Hoffman
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
| | - Brett D Keiper
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
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Robert VJ, Garvis S, Palladino F. Repression of somatic cell fate in the germline. Cell Mol Life Sci 2015; 72:3599-620. [PMID: 26043973 PMCID: PMC11113910 DOI: 10.1007/s00018-015-1942-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 05/26/2015] [Accepted: 05/27/2015] [Indexed: 01/13/2023]
Abstract
Germ cells must transmit genetic information across generations, and produce gametes while also maintaining the potential to form all cell types after fertilization. Preventing the activation of somatic programs is, therefore, crucial to the maintenance of germ cell identity. Studies in Caenorhabditis elegans, Drosophila melanogaster, and mouse have revealed both similarities and differences in how somatic gene expression is repressed in germ cells, thereby preventing their conversion into somatic tissues. This review will focus on recent developments in our understanding of how global or gene-specific transcriptional repression, chromatin regulation, and translational repression operate in the germline to maintain germ cell identity and repress somatic differentiation programs.
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Affiliation(s)
- Valérie J Robert
- Ecole Normale Supérieure de Lyon, Université de Lyon, 46 allée d'Italie, 69007, Lyon, France
| | - Steve Garvis
- Ecole Normale Supérieure de Lyon, Université de Lyon, 46 allée d'Italie, 69007, Lyon, France
| | - Francesca Palladino
- Ecole Normale Supérieure de Lyon, Université de Lyon, 46 allée d'Italie, 69007, Lyon, France.
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Abstract
Germ cells are the special cells in the body that undergo meiosis to generate gametes and subsequently entire new organisms after fertilization, a process that continues generation after generation. Recent studies have expanded our understanding of the factors and mechanisms that specify germ cell fate, including the partitioning of maternally supplied 'germ plasm', inheritance of epigenetic memory and expression of transcription factors crucial for primordial germ cell (PGC) development. Even after PGCs are specified, germline fate is labile and thus requires protective mechanisms, such as global transcriptional repression, chromatin state alteration and translation of only germline-appropriate transcripts. Findings from diverse species continue to provide insights into the shared and divergent needs of these special reproductive cells.
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Affiliation(s)
- Susan Strome
- Molecular, Cell &Developmental Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Dustin Updike
- Kathryn W. Davis Center for Regenerative Biology &Medicine, Mount Desert Island Biological Laboratory, Bar Harbor, Maine 04672, USA
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Butuči M, Williams AB, Wong MM, Kramer B, Michael WM. Zygotic Genome Activation Triggers Chromosome Damage and Checkpoint Signaling in C. elegans Primordial Germ Cells. Dev Cell 2015; 34:85-95. [PMID: 26073019 DOI: 10.1016/j.devcel.2015.04.019] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Revised: 03/17/2015] [Accepted: 04/24/2015] [Indexed: 01/05/2023]
Abstract
Recent findings have identified highly transcribed genes as a source of genome instability; however, the degree to which large-scale shifts in transcriptional activity cause DNA damage was not known. One example of a large-scale shift in transcriptional activity occurs during development, when maternal regulators are destroyed and zygotic genome activation (ZGA) occurs. Here, we show that ZGA triggers widespread chromosome damage in the primordial germ cells of the nematode C. elegans. We show that ZGA-induced DNA damage activates a checkpoint response, the damage is repaired by factors required for inter-sister homologous recombination, and topoisomerase II plays a role in generating the damage. These findings identify ZGA as a source of intrinsic genome instability in the germline and suggest that genome destabilization may be a general consequence of extreme shifts in cellular transcriptional load.
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Affiliation(s)
- Melina Butuči
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Ashley B Williams
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Matthew M Wong
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Brendan Kramer
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - W Matthew Michael
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA.
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Ho VWS, Wong MK, An X, Guan D, Shao J, Ng HCK, Ren X, He K, Liao J, Ang Y, Chen L, Huang X, Yan B, Xia Y, Chan LLH, Chow KL, Yan H, Zhao Z. Systems-level quantification of division timing reveals a common genetic architecture controlling asynchrony and fate asymmetry. Mol Syst Biol 2015; 11:814. [PMID: 26063786 PMCID: PMC4501849 DOI: 10.15252/msb.20145857] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Coordination of cell division timing is crucial for proper cell fate specification and tissue growth. However, the differential regulation of cell division timing across or within cell types during metazoan development remains poorly understood. To elucidate the systems-level genetic architecture coordinating division timing, we performed a high-content screening for genes whose depletion produced a significant reduction in the asynchrony of division between sister cells (ADS) compared to that of wild-type during Caenorhabditis elegans embryogenesis. We quantified division timing using 3D time-lapse imaging followed by computer-aided lineage analysis. A total of 822 genes were selected for perturbation based on their conservation and known roles in development. Surprisingly, we find that cell fate determinants are not only essential for establishing fate asymmetry, but also are imperative for setting the ADS regardless of cellular context, indicating a common genetic architecture used by both cellular processes. The fate determinants demonstrate either coupled or separate regulation between the two processes. The temporal coordination appears to facilitate cell migration during fate specification or tissue growth. Our quantitative dataset with cellular resolution provides a resource for future analyses of the genetic control of spatial and temporal coordination during metazoan development.
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Affiliation(s)
- Vincy Wing Sze Ho
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Ming-Kin Wong
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Xiaomeng An
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Daogang Guan
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Jiaofang Shao
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Hon Chun Kaoru Ng
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Xiaoliang Ren
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Kan He
- Department of Biology, Hong Kong Baptist University, Hong Kong, China Center for Stem Cell and Translational Medicine, School of Life Sciences Anhui University, Hefei, China
| | - Jinyue Liao
- Division of Life Science and Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Yingjin Ang
- Division of Life Science and Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Long Chen
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - Xiaotai Huang
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - Bin Yan
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Yiji Xia
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Leanne Lai Hang Chan
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - King Lau Chow
- Division of Life Science and Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Hong Yan
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong, China State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Hong Kong, China
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Osborne Nishimura E, Zhang JC, Werts AD, Goldstein B, Lieb JD. Asymmetric transcript discovery by RNA-seq in C. elegans blastomeres identifies neg-1, a gene important for anterior morphogenesis. PLoS Genet 2015; 11:e1005117. [PMID: 25875092 PMCID: PMC4395330 DOI: 10.1371/journal.pgen.1005117] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 03/03/2015] [Indexed: 11/23/2022] Open
Abstract
After fertilization but prior to the onset of zygotic transcription, the C. elegans zygote cleaves asymmetrically to create the anterior AB and posterior P1 blastomeres, each of which goes on to generate distinct cell lineages. To understand how patterns of RNA inheritance and abundance arise after this first asymmetric cell division, we pooled hand-dissected AB and P1 blastomeres and performed RNA-seq. Our approach identified over 200 asymmetrically abundant mRNA transcripts. We confirmed symmetric or asymmetric abundance patterns for a subset of these transcripts using smFISH. smFISH also revealed heterogeneous subcellular patterning of the P1-enriched transcripts chs-1 and bpl-1. We screened transcripts enriched in a given blastomere for embryonic defects using RNAi. The gene neg-1 (F32D1.6) encoded an AB-enriched (anterior) transcript and was required for proper morphology of anterior tissues. In addition, analysis of the asymmetric transcripts yielded clues regarding the post-transcriptional mechanisms that control cellular mRNA abundance during asymmetric cell divisions, which are common in developing organisms.
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Affiliation(s)
- Erin Osborne Nishimura
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jay C. Zhang
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Adam D. Werts
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Bob Goldstein
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jason D. Lieb
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Human Genetics, University of Chicago, Chicago, Illinois, United States of America
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Griffin EE. Cytoplasmic localization and asymmetric division in the early embryo of Caenorhabditis elegans. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 4:267-82. [PMID: 25764455 DOI: 10.1002/wdev.177] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 12/16/2014] [Accepted: 01/04/2015] [Indexed: 11/09/2022]
Abstract
During the initial cleavages of the Caenorhabditis elegans embryo, a series of rapid and invariant asymmetric cell divisions pattern the fate, size, and position of four somatic blastomeres and a single germline blastomere. These asymmetric divisions are orchestrated by a collection of maternally deposited factors that are initially symmetrically distributed in the newly fertilized embryo. Maturation of the sperm-derived centrosome in the posterior cytoplasm breaks this symmetry by triggering a dramatic and highly stereotyped partitioning of these maternal factors. A network of conserved cell polarity regulators, the PAR proteins, form distinct anterior and posterior domains at the cell cortex. From these domains, the PAR proteins direct the segregation of somatic and germline factors into opposing regions of the cytoplasm such that, upon cell division, they are preferentially inherited by the somatic blastomere or the germline blastomere, respectively. The segregation of these factors is controlled, at least in part, by a series of reaction-diffusion mechanisms that are asymmetrically deployed along the anterior/posterior axis. The characterization of these mechanisms has important implications for our understanding of how cells are polarized and how spatial organization is generated in the cytoplasm. For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Erik E Griffin
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA
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