1
|
Blundon JM, Cesar BI, Bae JW, Čavka I, Haversat J, Ries J, Köhler S, Kim Y. Skp1 proteins are structural components of the synaptonemal complex in C. elegans. SCIENCE ADVANCES 2024; 10:eadl4876. [PMID: 38354250 PMCID: PMC10866564 DOI: 10.1126/sciadv.adl4876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 01/12/2024] [Indexed: 02/16/2024]
Abstract
The synaptonemal complex (SC) is a zipper-like protein assembly that links homologous chromosomes to regulate recombination and segregation during meiosis. The SC has been notoriously refractory to in vitro reconstitution, thus leaving its molecular organization largely unknown. Here, we report a moonlighting function of two paralogous S-phase kinase-associated protein 1 (Skp1)-related proteins (SKR-1 and SKR-2), well-known adaptors of the Skp1-Cul1-F-box (SCF) ubiquitin ligase, as the key missing components of the SC in Caenorhabditis elegans. SKR proteins repurpose their SCF-forming interfaces to dimerize and interact with meiosis-specific SC proteins, thereby driving synapsis independent of SCF activity. SKR-1 enables the formation of the long-sought-after soluble complex with previously identified SC proteins in vitro, which we propose it to represent a complete SC building block. Our findings demonstrate how a conserved cell cycle regulator has been co-opted to interact with rapidly evolving meiotic proteins to construct the SC and provide a foundation for understanding its structure and assembly mechanisms.
Collapse
Affiliation(s)
- Joshua M. Blundon
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Brenda I. Cesar
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Jung Woo Bae
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Ivana Čavka
- The European Molecular Biology Laboratory, Heidelberg, Germany
- Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Jocelyn Haversat
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Jonas Ries
- The European Molecular Biology Laboratory, Heidelberg, Germany
| | - Simone Köhler
- The European Molecular Biology Laboratory, Heidelberg, Germany
| | - Yumi Kim
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| |
Collapse
|
2
|
Mazzetto M, Gonzalez LE, Sanchez N, Reinke V. Characterization of the distribution and dynamics of chromatin states in the C. elegans germline reveals substantial H3K4me3 remodeling during oogenesis. Genome Res 2024; 34:57-69. [PMID: 38164610 PMCID: PMC10903938 DOI: 10.1101/gr.278247.123] [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] [Received: 07/03/2023] [Accepted: 12/19/2023] [Indexed: 01/03/2024]
Abstract
Chromatin organization in the C. elegans germline is tightly regulated and critical for germ cell differentiation. Although certain germline epigenetic regulatory mechanisms have been identified, how they influence chromatin structure and ultimately gene expression remains unclear, in part because most genomic studies have focused on data collected from intact worms comprising both somatic and germline tissues. We therefore analyzed histone modification and chromatin accessibility data from isolated germ nuclei representing undifferentiated proliferating and meiosis I populations to define chromatin states. We correlated these states with overall transcript abundance, spatiotemporal expression patterns, and the function of small RNA pathways. Because the essential role of the germline is to transmit genetic information and establish gene expression in the early embryo, we compared epigenetic and transcriptomic profiles from undifferentiated germ cells to those of embryos to define the epigenetic changes during this developmental transition. The active histone modification H3K4me3 shows particularly dynamic remodeling as germ cells differentiate into oocytes, which suggests a mechanism for establishing early transcription of essential genes during zygotic genome activation. This analysis highlights the dynamism of the chromatin landscape across developmental transitions and provides a resource for future investigation into epigenetic regulatory mechanisms in germ cells.
Collapse
Affiliation(s)
| | - Lauren E Gonzalez
- Department of Genetics, Yale University, New Haven, Connecticut 06520, USA
| | - Nancy Sanchez
- Department of Genetics, Yale University, New Haven, Connecticut 06520, USA
| | - Valerie Reinke
- Department of Genetics, Yale University, New Haven, Connecticut 06520, USA
| |
Collapse
|
3
|
Chen S, Phillips CM. HRDE-2 drives small RNA specificity for the nuclear Argonaute protein HRDE-1. Nat Commun 2024; 15:957. [PMID: 38302462 PMCID: PMC10834429 DOI: 10.1038/s41467-024-45245-8] [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: 08/23/2023] [Accepted: 01/18/2024] [Indexed: 02/03/2024] Open
Abstract
RNA interference (RNAi) is a conserved gene silencing process that exists in diverse organisms to protect genome integrity and regulate gene expression. In C. elegans, the majority of RNAi pathway proteins localize to perinuclear, phase-separated germ granules, which are comprised of sub-domains referred to as P granules, Mutator foci, Z granules, and SIMR foci. However, the protein components and function of the newly discovered SIMR foci are unknown. Here we demonstrate that HRDE-2 localizes to SIMR foci and interacts with the germline nuclear Argonaute HRDE-1 in its small RNA unbound state. In the absence of HRDE-2, HRDE-1 exclusively loads CSR-class 22G-RNAs rather than WAGO-class 22G-RNAs, resulting in inappropriate H3K9me3 deposition on CSR-target genes. Thus, our study demonstrates that the recruitment of unloaded HRDE-1 to germ granules, mediated by HRDE-2, is critical to ensure that the correct small RNAs are used to guide nuclear RNA silencing in the C. elegans germline.
Collapse
Affiliation(s)
- Shihui Chen
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA
| | - Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA.
| |
Collapse
|
4
|
Robert VJ, Caron M, Gely L, Adrait A, Pakulska V, Couté Y, Chevalier M, Riedel CG, Bedet C, Palladino F. SIN-3 acts in distinct complexes to regulate the germline transcriptional program in Caenorhabditis elegans. Development 2023; 150:dev201755. [PMID: 38771303 PMCID: PMC10617626 DOI: 10.1242/dev.201755] [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: 03/08/2023] [Accepted: 09/18/2023] [Indexed: 10/12/2023]
Abstract
The transcriptional co-regulator SIN3 influences gene expression through multiple interactions that include histone deacetylases. Haploinsufficiency and mutations in SIN3 are the underlying cause of Witteveen-Kolk syndrome and related intellectual disability and autism syndromes, emphasizing its key role in development. However, little is known about the diversity of its interactions and functions in developmental processes. Here, we show that loss of SIN-3, the single SIN3 homolog in Caenorhabditis elegans, results in maternal-effect sterility associated with de-regulation of the germline transcriptome, including de-silencing of X-linked genes. We identify at least two distinct SIN3 complexes containing specific histone deacetylases and show that they differentially contribute to fertility. Single-cell, single-molecule fluorescence in situ hybridization reveals that in sin-3 mutants the X chromosome becomes re-expressed prematurely and in a stochastic manner in individual germ cells, suggesting a role for SIN-3 in its silencing. Furthermore, we identify histone residues whose acetylation increases in the absence of SIN-3. Together, this work provides a powerful framework for the in vivo study of SIN3 and associated proteins.
Collapse
Affiliation(s)
- Valerie J. Robert
- Laboratory of Biology and Modeling of the Cell, UMR5239 CNRS/Ecole Normale Supérieure de Lyon, INSERM U1210, UMS 3444 Biosciences Lyon Gerland, Université de Lyon, 69007 Lyon, France
| | - Matthieu Caron
- Laboratory of Biology and Modeling of the Cell, UMR5239 CNRS/Ecole Normale Supérieure de Lyon, INSERM U1210, UMS 3444 Biosciences Lyon Gerland, Université de Lyon, 69007 Lyon, France
| | - Loic Gely
- Laboratory of Biology and Modeling of the Cell, UMR5239 CNRS/Ecole Normale Supérieure de Lyon, INSERM U1210, UMS 3444 Biosciences Lyon Gerland, Université de Lyon, 69007 Lyon, France
| | - Annie Adrait
- Grenoble Alpes, CEA, Inserm, UA13 BGE, CNRS, CEA, FR2048, 38000 Grenoble, France
| | - Victoria Pakulska
- Grenoble Alpes, CEA, Inserm, UA13 BGE, CNRS, CEA, FR2048, 38000 Grenoble, France
| | - Yohann Couté
- Grenoble Alpes, CEA, Inserm, UA13 BGE, CNRS, CEA, FR2048, 38000 Grenoble, France
| | - Manon Chevalier
- Department of Biosciences and Nutrition, Karolinska Institutet, Blickagången 16, 14157 Huddinge, Sweden
| | - Christian G. Riedel
- Department of Biosciences and Nutrition, Karolinska Institutet, Blickagången 16, 14157 Huddinge, Sweden
| | - Cecile Bedet
- Laboratory of Biology and Modeling of the Cell, UMR5239 CNRS/Ecole Normale Supérieure de Lyon, INSERM U1210, UMS 3444 Biosciences Lyon Gerland, Université de Lyon, 69007 Lyon, France
| | - Francesca Palladino
- Laboratory of Biology and Modeling of the Cell, UMR5239 CNRS/Ecole Normale Supérieure de Lyon, INSERM U1210, UMS 3444 Biosciences Lyon Gerland, Université de Lyon, 69007 Lyon, France
| |
Collapse
|
5
|
Liu C, Rex R, Lung Z, Wang JS, Wu F, Kim HJ, Zhang L, Sohn LL, Dernburg AF. A cooperative network at the nuclear envelope counteracts LINC-mediated forces during oogenesis in C. elegans. SCIENCE ADVANCES 2023; 9:eabn5709. [PMID: 37436986 PMCID: PMC10337908 DOI: 10.1126/sciadv.abn5709] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 06/08/2023] [Indexed: 07/14/2023]
Abstract
Oogenesis involves transduction of mechanical forces from the cytoskeleton to the nuclear envelope (NE). In Caenorhabditis elegans, oocyte nuclei lacking the single lamin protein LMN-1 are vulnerable to collapse under forces mediated through LINC (linker of nucleoskeleton and cytoskeleton) complexes. Here, we use cytological analysis and in vivo imaging to investigate the balance of forces that drive this collapse and protect oocyte nuclei. We also use a mechano-node-pore sensing device to directly measure the effect of genetic mutations on oocyte nuclear stiffness. We find that nuclear collapse is not a consequence of apoptosis. It is promoted by dynein, which induces polarization of a LINC complex composed of Sad1 and UNC-84 homology 1 (SUN-1) and ZYGote defective 12 (ZYG-12). Lamins contribute to oocyte nuclear stiffness and cooperate with other inner nuclear membrane proteins to distribute LINC complexes and protect nuclei from collapse. We speculate that a similar network may protect oocyte integrity during extended oocyte arrest in mammals.
Collapse
Affiliation(s)
- Chenshu Liu
- California Institute for Quantitative Biosciences (QB3) and Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Rachel Rex
- Department of Mechanical Engineering, University of California Berkeley, Berkeley, CA 94720, USA
| | - Zoe Lung
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - John S. Wang
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Fan Wu
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Hyung Jun Kim
- California Institute for Quantitative Biosciences (QB3) and Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Liangyu Zhang
- California Institute for Quantitative Biosciences (QB3) and Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Lydia L. Sohn
- Department of Mechanical Engineering, University of California Berkeley, Berkeley, CA 94720, USA
| | - Abby F. Dernburg
- California Institute for Quantitative Biosciences (QB3) and Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
- Department of Biological Sciences and Engineering, Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| |
Collapse
|
6
|
Sanchez N, Gonzalez LE, Reinke V. The Upstream Sequence Transcription Complex Dictates Nucleosome Positioning and Promoter Accessibility at piRNA Genes in the C. elegans Germ Line. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.10.540274. [PMID: 37215016 PMCID: PMC10197682 DOI: 10.1101/2023.05.10.540274] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The piRNA pathway is a conserved germline-specific small RNA pathway that ensures genomic integrity and continued fertility. In C. elegans and other nematodes, Type-I piRNA precursor transcripts are expressed from over 10,000 small, independently regulated genes clustered within two discrete domains of 1.5 and 3.5 MB on Chromosome IV. These large clusters likely play a significant role in promoting germline-specific expression of piRNAs, but the underlying mechanisms are unclear. By examining the chromatin environment specifically in isolated germ nuclei, we demonstrate that piRNA clusters are located in closed chromatin, and confirm the enrichment for the inactive histone modification H3K27me3. We further show that the piRNA biogenesis factor USTC (Upstream Sequence Transcription Complex) plays two roles - it promotes a strong association of nucleosomes throughout the piRNA clusters, and it organizes the local nucleosome environment to direct the exposure of individual piRNA genes. Overall, this work reveals new insight into how chromatin state coordinates transcriptional regulation over large genomic domains, which has implications for understanding global genome organization in the germ line.
Collapse
Affiliation(s)
- Nancy Sanchez
- Department of Genetics, Yale University School of Medicine, New Haven CT 06520
| | - Lauren E Gonzalez
- Department of Genetics, Yale University School of Medicine, New Haven CT 06520
| | - Valerie Reinke
- Department of Genetics, Yale University School of Medicine, New Haven CT 06520
| |
Collapse
|
7
|
Butto T, Mungikar K, Baumann P, Winter J, Lutz B, Gerber S. Nuclei on the Rise: When Nuclei-Based Methods Meet Next-Generation Sequencing. Cells 2023; 12:cells12071051. [PMID: 37048124 PMCID: PMC10093037 DOI: 10.3390/cells12071051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 03/22/2023] [Accepted: 03/27/2023] [Indexed: 04/03/2023] Open
Abstract
In the last decade, we have witnessed an upsurge in nuclei-based studies, particularly coupled with next-generation sequencing. Such studies aim at understanding the molecular states that exist in heterogeneous cell populations by applying increasingly more affordable sequencing approaches, in addition to optimized methodologies developed to isolate and select nuclei. Although these powerful new methods promise unprecedented insights, it is important to understand and critically consider the associated challenges. Here, we provide a comprehensive overview of the rise of nuclei-based studies and elaborate on their advantages and disadvantages, with a specific focus on their utility for transcriptomic sequencing analyses. Improved designs and appropriate use of the various experimental strategies will result in acquiring biologically accurate and meaningful information.
Collapse
Affiliation(s)
- Tamer Butto
- Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University, 55128 Mainz, Germany
- Correspondence: (T.B.); (S.G.); Tel.: +49-(0)6131-39-27331 (S.G.)
| | - Kanak Mungikar
- Institute of Human Genetics, University Medical Center Mainz, 55131 Mainz, Germany
| | - Peter Baumann
- Faculty of Biology, Johannes Gutenberg-University, 55128 Mainz, Germany
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany
| | - Jennifer Winter
- Institute of Human Genetics, University Medical Center Mainz, 55131 Mainz, Germany
- Leibniz Institute for Resilience Research (LIR), 55122 Mainz, Germany
| | - Beat Lutz
- Leibniz Institute for Resilience Research (LIR), 55122 Mainz, Germany
- Institute of Physiological Chemistry, University Medical Center Mainz, 55128 Mainz, Germany
| | - Susanne Gerber
- Institute of Human Genetics, University Medical Center Mainz, 55131 Mainz, Germany
- Correspondence: (T.B.); (S.G.); Tel.: +49-(0)6131-39-27331 (S.G.)
| |
Collapse
|
8
|
Koutsoumparis A, Welp LM, Wulf A, Urlaub H, Meierhofer D, Börno S, Timmermann B, Busack I, Bringmann H. Sleep neuron depolarization promotes protective gene expression changes and FOXO activation. Curr Biol 2022; 32:2248-2262.e9. [DOI: 10.1016/j.cub.2022.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 02/09/2022] [Accepted: 04/06/2022] [Indexed: 11/16/2022]
|
9
|
Grandi FC, Modi H, Kampman L, Corces MR. Chromatin accessibility profiling by ATAC-seq. Nat Protoc 2022; 17:1518-1552. [PMID: 35478247 DOI: 10.1038/s41596-022-00692-9] [Citation(s) in RCA: 91] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 02/22/2022] [Indexed: 12/13/2022]
Abstract
The assay for transposase-accessible chromatin using sequencing (ATAC-seq) provides a simple and scalable way to detect the unique chromatin landscape associated with a cell type and how it may be altered by perturbation or disease. ATAC-seq requires a relatively small number of input cells and does not require a priori knowledge of the epigenetic marks or transcription factors governing the dynamics of the system. Here we describe an updated and optimized protocol for ATAC-seq, called Omni-ATAC, that is applicable across a broad range of cell and tissue types. The ATAC-seq workflow has five main steps: sample preparation, transposition, library preparation, sequencing and data analysis. This protocol details the steps to generate and sequence ATAC-seq libraries, with recommendations for sample preparation and downstream bioinformatic analysis. ATAC-seq libraries for roughly 12 samples can be generated in 10 h by someone familiar with basic molecular biology, and downstream sequencing analysis can be implemented using benchmarked pipelines by someone with basic bioinformatics skills and with access to a high-performance computing environment.
Collapse
Affiliation(s)
- Fiorella C Grandi
- Gladstone Institute of Neurological Disease, San Francisco, CA, USA.,Gladstone Institute of Data Science and Biotechnology, San Francisco, CA, USA.,Department of Neurology, University of California San Francisco, San Francisco, CA, USA
| | - Hailey Modi
- Gladstone Institute of Neurological Disease, San Francisco, CA, USA.,Gladstone Institute of Data Science and Biotechnology, San Francisco, CA, USA.,Department of Neurology, University of California San Francisco, San Francisco, CA, USA
| | - Lucas Kampman
- Gladstone Institute of Neurological Disease, San Francisco, CA, USA.,Gladstone Institute of Data Science and Biotechnology, San Francisco, CA, USA.,Department of Neurology, University of California San Francisco, San Francisco, CA, USA
| | - M Ryan Corces
- Gladstone Institute of Neurological Disease, San Francisco, CA, USA. .,Gladstone Institute of Data Science and Biotechnology, San Francisco, CA, USA. .,Department of Neurology, University of California San Francisco, San Francisco, CA, USA.
| |
Collapse
|
10
|
Woronik A, Kiontke K, Jallad RS, Herrera RA, Fitch DHA. Laser Microdissection for Species-Agnostic Single-Tissue Applications. J Vis Exp 2022:10.3791/63666. [PMID: 35435919 PMCID: PMC9976942 DOI: 10.3791/63666] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Single-cell methodologies have revolutionized the analysis of the transcriptomes of specific cell types. However, they often require species-specific genetic "toolkits," such as promoters driving tissue-specific expression of fluorescent proteins. Further, protocols that disrupt tissues to isolate individual cells remove cells from their native environment (e.g., signaling from neighbors) and may result in stress responses or other differences from native gene expression states. In the present protocol, laser microdissection (LMD) is optimized to isolate individual nematode tail tips for the study of gene expression during male tail tip morphogenesis. LMD allows the isolation of a portion of the animal without the need for cellular disruption or species-specific toolkits and is thus applicable to any species. Subsequently, single-cell RNA-seq library preparation protocols such as CEL-Seq2 can be applied to LMD-isolated single tissues and analyzed using standard pipelines, given that a well-annotated genome or transcriptome is available for the species. Such data can be used to establish how conserved or different the transcriptomes are that underlie the development of that tissue in different species. Limitations include the ability to cut out the tissue of interest and the sample size. A power analysis shows that as few as 70 tail tips per condition are required for 80% power. Tight synchronization of development is needed to obtain this number of animals at the same developmental stage. Thus, a method to synchronize animals at 1 h intervals is also described.
Collapse
Affiliation(s)
- Alyssa Woronik
- Center for Developmental Genetics, New York University,Sacred Heart University
| | - Karin Kiontke
- Center for Developmental Genetics, New York University
| | | | | | | |
Collapse
|
11
|
McManus CE, Mazzetto M, Wei G, Han M, Reinke V. The zinc-finger protein OEF-1 stabilizes histone modification patterns and promotes efficient splicing in the C. elegans germ line. G3-GENES GENOMES GENETICS 2021; 11:6370151. [PMID: 34519784 PMCID: PMC8664474 DOI: 10.1093/g3journal/jkab329] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 09/07/2021] [Indexed: 12/03/2022]
Abstract
To ensure stable transmission of genetic information to the next generation, germ cells frequently silence sex chromosomes, as well as autosomal loci that promote inappropriate differentiation programs. In Caenorhabditis elegans, silenced and active genomic domains are established in germ cells by the histone modification complexes MES-2/3/6 and MES-4, which promote silent and active chromatin states, respectively. These states are generally mutually exclusive and modulation of one state influences the pattern of the other. Here, we identify the zinc-finger protein OEF-1 as a novel modifier of this epigenetic balance in the C. elegans germline. Loss of oef-1 genetically enhances mes mutant phenotypes. Moreover, OEF-1 binding correlates with the active modification H3K36me3 and sustains H3K36me3 levels in the absence of MES-4 activity. OEF-1 also promotes efficient mRNA splicing activity, a process that is influenced by H3K36me3 levels. Finally, OEF-1 limits deposition of the silencing modification H3K27me3 on the X chromosome and at repressed autosomal loci. We propose that OEF-1 might act as an intermediary to mediate the downstream effects of H3K36me3 that promote transcript integrity, and indirectly affect gene silencing as a consequence.
Collapse
Affiliation(s)
- Catherine E McManus
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Mariateresa Mazzetto
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Guifeng Wei
- Developmental Epigenetics, Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Mei Han
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Valerie Reinke
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, USA
| |
Collapse
|
12
|
Beltran T, Pahita E, Ghosh S, Lenhard B, Sarkies P. Integrator is recruited to promoter-proximally paused RNA Pol II to generate Caenorhabditis elegans piRNA precursors. EMBO J 2021; 40:e105564. [PMID: 33340372 PMCID: PMC7917550 DOI: 10.15252/embj.2020105564] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 10/14/2020] [Accepted: 10/27/2020] [Indexed: 12/29/2022] Open
Abstract
Piwi-interacting RNAs (piRNAs) play key roles in germline development and genome defence in metazoans. In C. elegans, piRNAs are transcribed from > 15,000 discrete genomic loci by RNA polymerase II (Pol II), resulting in 28 nt short-capped piRNA precursors. Here, we investigate transcription termination at piRNA loci. We show that the Integrator complex, which terminates snRNA transcription, is recruited to piRNA loci. Moreover, we demonstrate that the catalytic activity of Integrator cleaves nascent capped piRNA precursors associated with promoter-proximal Pol II, resulting in termination of transcription. Loss of Integrator activity, however, does not result in transcriptional readthrough at the majority of piRNA loci. Taken together, our results draw new parallels between snRNA and piRNA biogenesis in nematodes and provide evidence of a role for the Integrator complex as a terminator of promoter-proximal RNA polymerase II during piRNA biogenesis.
Collapse
Affiliation(s)
- Toni Beltran
- MRC London Institute of Medical SciencesLondonUK
- Institute of Clinical SciencesImperial College LondonLondonUK
- Present address:
Centre for Genomic RegulationBarcelonaSpain
| | - Elena Pahita
- MRC London Institute of Medical SciencesLondonUK
- Institute of Clinical SciencesImperial College LondonLondonUK
| | - Subhanita Ghosh
- MRC London Institute of Medical SciencesLondonUK
- Institute of Clinical SciencesImperial College LondonLondonUK
| | - Boris Lenhard
- MRC London Institute of Medical SciencesLondonUK
- Institute of Clinical SciencesImperial College LondonLondonUK
| | - Peter Sarkies
- MRC London Institute of Medical SciencesLondonUK
- Institute of Clinical SciencesImperial College LondonLondonUK
| |
Collapse
|
13
|
Abstract
Two distinct groups of parasitic nematodes use programmed DNA elimination to silence germline-expressed genes in the somatic cells (ascarids) or for sex determination (Strongyloides spp.). In the ascarids, DNA is lost only in pre-somatic cells during early embryogenesis, leading to a reduced somatic genome compared to the intact germ cell genome. Comparative genome analysis has provided information on the retained vs. eliminated sequences, DNA breaks, a full chromosome view on DNA elimination, and the evolutionary conservation of DNA elimination among ascarids. These studies have revealed novel insights into the functions and mechanisms of DNA elimination and provided a reference for in-depth molecular analysis of DNA elimination. Here, I describe the genomics methods we used to study programmed DNA elimination, focusing on the parasitic nematode Ascaris.
Collapse
Affiliation(s)
- Jianbin Wang
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA. .,UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA.
| |
Collapse
|
14
|
DasGupta A, Lee TL, Li C, Saltzman AL. Emerging Roles for Chromo Domain Proteins in Genome Organization and Cell Fate in C. elegans. Front Cell Dev Biol 2020; 8:590195. [PMID: 33195254 PMCID: PMC7649781 DOI: 10.3389/fcell.2020.590195] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 09/08/2020] [Indexed: 11/28/2022] Open
Abstract
In most eukaryotes, the genome is packaged with histones and other proteins to form chromatin. One of the major mechanisms for chromatin regulation is through post-translational modification of histone proteins. Recognition of these modifications by effector proteins, often dubbed histone “readers,” provides a link between the chromatin landscape and gene regulation. The diversity of histone reader proteins for each modification provides an added layer of regulatory complexity. In this review, we will focus on the roles of chromatin organization modifier (chromo) domain containing proteins in the model nematode, Caenorhabditis elegans. An amenability to genetic and cell biological approaches, well-studied development and a short life cycle make C. elegans a powerful system to investigate the diversity of chromo domain protein functions in metazoans. We will highlight recent insights into the roles of chromo domain proteins in the regulation of heterochromatin and the spatial conformation of the genome as well as their functions in cell fate, fertility, small RNA pathways and transgenerational epigenetic inheritance. The spectrum of different chromatin readers may represent a layer of regulation that integrates chromatin landscape, genome organization and gene expression.
Collapse
Affiliation(s)
- Abhimanyu DasGupta
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Tammy L Lee
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Chengyin Li
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Arneet L Saltzman
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
15
|
Robert VJ, Knutson AK, Rechtsteiner A, Garvis S, Yvert G, Strome S, Palladino F. Caenorhabditis elegans SET1/COMPASS Maintains Germline Identity by Preventing Transcriptional Deregulation Across Generations. Front Cell Dev Biol 2020; 8:561791. [PMID: 33072747 PMCID: PMC7536326 DOI: 10.3389/fcell.2020.561791] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 08/18/2020] [Indexed: 12/11/2022] Open
Abstract
Chromatin regulators contribute to the maintenance of the germline transcriptional program. In the absence of SET-2, the Caenorhabditis elegans homolog of the SET1/COMPASS H3 Lys4 (H3K4) methyltransferase, animals show transgenerational loss of germline identity, leading to sterility. To identify transcriptional signatures associated with progressive loss of fertility, we performed expression profiling of set-2 mutant germlines across generations. We identify a subset of genes whose misexpression is first observed in early generations, a step we refer to as priming; their misexpression then further progresses in late generations, as animals reach sterility. Analysis of misregulated genes shows that down-regulation of germline genes, expression of somatic transcriptional programs, and desilencing of the X-chromosome are concurrent events leading to loss of germline identity in both early and late generations. Upregulation of transcription factor LIN-15B, the C/EBP homolog CEBP-1, and TGF-β pathway components strongly contribute to loss of fertility, and RNAi inactivation of cebp-1 and TGF-β/Smad signaling delays the onset of sterility, showing they individually contribute to maintenance of germ cell identity. Our approach therefore identifies genes and pathways whose misexpression actively contributes to the loss of germ cell fate. More generally, our data shows how loss of a chromatin regulator in one generation leads to transcriptional changes that are amplified over subsequent generations, ultimately leading to loss of appropriate cell fate.
Collapse
Affiliation(s)
- Valérie J Robert
- Laboratory of Biology and Modeling of the Cell, Ecole Normale Supérieure de Lyon, CNRS, Université Claude Bernard de Lyon, Université de Lyon, Lyon, France
| | - Andrew K Knutson
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Andreas Rechtsteiner
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Steven Garvis
- Laboratory of Biology and Modeling of the Cell, Ecole Normale Supérieure de Lyon, CNRS, Université Claude Bernard de Lyon, Université de Lyon, Lyon, France
| | - Gaël Yvert
- Laboratory of Biology and Modeling of the Cell, Ecole Normale Supérieure de Lyon, CNRS, Université Claude Bernard de Lyon, Université de Lyon, Lyon, France
| | - Susan Strome
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Francesca Palladino
- Laboratory of Biology and Modeling of the Cell, Ecole Normale Supérieure de Lyon, CNRS, Université Claude Bernard de Lyon, Université de Lyon, Lyon, France
| |
Collapse
|
16
|
Rogers AK, Phillips CM. RNAi pathways repress reprogramming of C. elegans germ cells during heat stress. Nucleic Acids Res 2020; 48:4256-4273. [PMID: 32187370 PMCID: PMC7192617 DOI: 10.1093/nar/gkaa174] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 03/02/2020] [Accepted: 03/10/2020] [Indexed: 01/08/2023] Open
Abstract
Repression of cellular reprogramming in germ cells is critical to maintaining cell fate and fertility. When germ cells mis-express somatic genes they can be directly converted into other cell types, resulting in loss of totipotency and reproductive potential. Identifying the molecular mechanisms that coordinate these cell fate decisions is an active area of investigation. Here we show that RNAi pathways play a key role in maintaining germline gene expression and totipotency after heat stress. By examining transcriptional changes that occur in mut-16 mutants, lacking a key protein in the RNAi pathway, at elevated temperature we found that genes normally expressed in the soma are mis-expressed in germ cells. Furthermore, these genes displayed increased chromatin accessibility in the germlines of mut-16 mutants at elevated temperature. These findings indicate that the RNAi pathway plays a key role in preventing aberrant expression of somatic genes in the germline during heat stress. This regulation occurs in part through the maintenance of germline chromatin, likely acting through the nuclear RNAi pathway. Identification of new pathways governing germ cell reprogramming is critical to understanding how cells maintain proper gene expression and may provide key insights into how cell identity is lost in some germ cell tumors.
Collapse
Affiliation(s)
- Alicia K Rogers
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| |
Collapse
|