1
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van den Berg W, Gupta BP. Genome-Wide Temporal Gene Expression Reveals a Post-Reproductive Shift in the Nematode Caenorhabditis briggsae. Genome Biol Evol 2025; 17:evaf057. [PMID: 40171711 PMCID: PMC11992569 DOI: 10.1093/gbe/evaf057] [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: 08/24/2024] [Revised: 03/11/2025] [Accepted: 03/24/2025] [Indexed: 04/04/2025] Open
Abstract
The nematodes Caenorhabditis briggsae and its well-known cousin Caenorhabditis elegans offer many features for comparative investigations of genetic pathways that affect physiological processes. Reproduction is one such process that directly impacts longevity due to its significant energetic demands. To study gene expression changes during reproductive and post-reproductive phases in both these nematodes, we conducted whole-genome transcriptome profiling at various adult stages. The results revealed that the majority of differentially expressed (DE) genes were downregulated during the reproductive period in both species. Interestingly, in C. briggsae, this trend reversed during post-reproduction, with three-quarters of the DE genes becoming upregulated. Additionally, a smaller set of DE genes showed an opposite expression trend, i.e. upregulation followed by post-reproductive downregulation. Overall, we termed this phenomenon the "post-reproductive shift". In contrast, the post-reproductive shift was much less pronounced in C. elegans. In C. briggsae, DE genes were enriched in processes related to the matrisome, muscle development and function during the reproductive period. Post-reproductive downregulated genes were enriched in DNA damage repair, stress response, and immune response. Additionally, terms related to fatty acid metabolism, catabolism, and transcriptional regulation exhibited complex patterns. Experimental manipulations in C. briggsae to affect their reproductive status predictably altered gene expression, providing in vivo support for the post-reproductive shift. Overall, our study reveals novel gene expression patterns during reproductive and post-reproductive changes in C. briggsae. The data provide a valuable resource for cross-sectional comparative studies in nematodes and other animal models to understand evolution of genetic pathways affecting reproduction and aging.
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Affiliation(s)
- Wouter van den Berg
- Department of Biology, McMaster University, Hamilton, Ontario L8S-4K1, Canada
| | - Bhagwati P Gupta
- Department of Biology, McMaster University, Hamilton, Ontario L8S-4K1, Canada
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2
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Cao W, Fan Q, Amparado G, Begic D, Godini R, Gopal S, Pocock R. A nucleic acid binding protein map of germline regulation in Caenorhabditis elegans. Nat Commun 2024; 15:6884. [PMID: 39128930 PMCID: PMC11317507 DOI: 10.1038/s41467-024-51212-0] [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: 05/31/2024] [Accepted: 08/01/2024] [Indexed: 08/13/2024] Open
Abstract
Fertility requires the faithful proliferation of germ cells and their differentiation into gametes. Controlling these cellular states demands precise timing and expression of gene networks. Nucleic acid binding proteins (NBPs) play critical roles in gene expression networks that influence germ cell development. There has, however, been no functional analysis of the entire NBP repertoire in controlling in vivo germ cell development. Here, we analyzed germ cell states and germline architecture to systematically investigate the function of 364 germline-expressed NBPs in the Caenorhabditis elegans germ line. Using germline-specific knockdown, automated germ cell counting, and high-content analysis of germ cell nuclei and plasma membrane organization, we identify 156 NBPs with discrete autonomous germline functions. By identifying NBPs that control the germ cell cycle, proliferation, differentiation, germline structure and fertility, we have created an atlas for mechanistic dissection of germ cell behavior and gamete production.
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Affiliation(s)
- Wei Cao
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, 3800, Australia.
| | - Qi Fan
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, 3800, Australia
| | - Gemmarie Amparado
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, 3800, Australia
| | - Dean Begic
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, 3800, Australia
| | - Rasoul Godini
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, 3800, Australia
| | - Sandeep Gopal
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, 3800, Australia.
- Lund Stem Cell Center, Department of Experimental Medical Science, Lund University, Lund, Sweden.
| | - Roger Pocock
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, 3800, Australia.
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3
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Tan CH, Wang TY, Park H, Lomenick B, Chou TF, Sternberg PW. Single-tissue proteomics in Caenorhabditis elegans reveals proteins resident in intestinal lysosome-related organelles. Proc Natl Acad Sci U S A 2024; 121:e2322588121. [PMID: 38861598 PMCID: PMC11194598 DOI: 10.1073/pnas.2322588121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Accepted: 05/06/2024] [Indexed: 06/13/2024] Open
Abstract
The nematode intestine is the primary site for nutrient uptake and storage as well as the synthesis of biomolecules; lysosome-related organelles known as gut granules are important for many of these functions. Aspects of intestine biology are not well understood, including the export of the nutrients it imports and the molecules it synthesizes, as well as the complete functions and protein content of the gut granules. Here, we report a mass spectrometry (MS)-based proteomic analysis of the intestine of the Caenorhabditis elegans and of its gut granules. Overall, we identified approximately 5,000 proteins each in the intestine and the gonad and showed that most of these proteins can be detected in samples extracted from a single worm, suggesting the feasibility of individual-level genetic analysis using proteomes. Comparing proteomes and published transcriptomes of the intestine and the gonad, we identified proteins that appear to be synthesized in the intestine and then transferred to the gonad. To identify gut granule proteins, we compared the proteome of individual intestines deficient in gut granules to the wild type. The identified gut granule proteome includes proteins known to be exclusively localized to the granules and additional putative gut granule proteins. We selected two of these putative gut granule proteins for validation via immunohistochemistry, and our successful confirmation of both suggests that our strategy was effective in identifying the gut granule proteome. Our results demonstrate the practicability of single-tissue MS-based proteomic analysis in small organisms and in its future utility.
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Affiliation(s)
- Chieh-Hsiang Tan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Ting-Yu Wang
- Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA91125
| | - Heenam Park
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Brett Lomenick
- Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA91125
| | - Tsui-Fen Chou
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
- Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA91125
| | - Paul W. Sternberg
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
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4
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Goetsch PD, Strome S. DREAM interrupted: severing LIN-35-MuvB association in Caenorhabditis elegans impairs DREAM function but not its chromatin localization. Genetics 2022; 221:iyac073. [PMID: 35554539 PMCID: PMC9252284 DOI: 10.1093/genetics/iyac073] [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: 11/26/2019] [Accepted: 04/19/2022] [Indexed: 11/14/2022] Open
Abstract
The mammalian pocket protein family, which includes the Retinoblastoma protein (pRb) and Rb-like pocket proteins p107 and p130, regulates entry into and exit from the cell cycle by repressing cell cycle gene expression. Although pRb plays a dominant role in mammalian systems, p107 and p130 are the ancestral pocket proteins. The Rb-like pocket proteins interact with the highly conserved 5-subunit MuvB complex and an E2F-DP transcription factor heterodimer, forming the DREAM (for Dp, Rb-like, E2F, and MuvB) complex. DREAM complex assembly on chromatin culminates in repression of target genes mediated by the MuvB subcomplex. Here, we examined how the Rb-like pocket protein contributes to DREAM formation and function by disrupting the interaction between the sole Caenorhabditis elegans pocket protein LIN-35 and the MuvB subunit LIN-52 using CRISPR/Cas9 targeted mutagenesis. A triple alanine substitution of LIN-52's LxCxE motif severed LIN-35-MuvB association and caused classical DREAM mutant phenotypes, including synthetic multiple vulvae, high-temperature arrest, and ectopic expression of germline genes in the soma. However, RNA-sequencing revealed limited upregulation of DREAM target genes when LIN-35-MuvB association was severed, as compared with gene upregulation following LIN-35 loss. Based on chromatin immunoprecipitation, disrupting LIN-35-MuvB association did not affect the chromatin localization of E2F-DP, LIN-35, or MuvB components. In a previous study, we showed that in worms lacking LIN-35, E2F-DP, and MuvB chromatin occupancy was reduced genome-wide. With LIN-35 present but unable to associate with MuvB, our study suggests that the E2F-DP-LIN-35 interaction promotes E2F-DP's chromatin localization, which we hypothesize supports MuvB chromatin occupancy indirectly through DNA. Altogether, this study highlights how the pocket protein's association with MuvB supports DREAM function but is not required for DREAM's chromatin occupancy.
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Affiliation(s)
- Paul D Goetsch
- Department of Biological Sciences, Michigan Technological University, Houghton, MI 49931, USA
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Susan Strome
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
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5
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Ouyang JPT, Zhang WL, Seydoux G. The conserved helicase ZNFX-1 memorializes silenced RNAs in perinuclear condensates. Nat Cell Biol 2022; 24:1129-1140. [PMID: 35739318 PMCID: PMC9276528 DOI: 10.1038/s41556-022-00940-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 05/11/2022] [Indexed: 01/23/2023]
Abstract
RNA-mediated interference (RNAi) is a conserved mechanism that uses small RNAs (sRNAs) to silence gene expression. In the Caenorhabditis elegans germline, transcripts targeted by sRNAs are used as templates for sRNA amplification to propagate silencing into the next generation. Here we show that RNAi leads to heritable changes in the distribution of nascent and mature transcripts that correlate with two parallel sRNA amplification loops. The first loop, dependent on the nuclear Argonaute HRDE-1, targets nascent transcripts and reduces but does not eliminate productive transcription at the locus. The second loop, dependent on the conserved helicase ZNFX-1, targets mature transcripts and concentrates them in perinuclear condensates. ZNFX-1 interacts with sRNA-targeted transcripts that have acquired poly(UG) tails and is required to sustain pUGylation and robust sRNA amplification in the inheriting generation. By maintaining a pool of transcripts for amplification, ZNFX-1 prevents premature extinction of the RNAi response and extends silencing into the next generation.
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Affiliation(s)
- John Paul Tsu Ouyang
- HHMI and Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Wenyan Lucy Zhang
- HHMI and Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Geraldine Seydoux
- HHMI and Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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6
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Jin X, Liu J, Wang S, Shi J, Zhao C, Xie H, Kang Y. E2f4 is required for intestinal and otolith development in zebrafish. J Cell Physiol 2022; 237:2690-2702. [DOI: 10.1002/jcp.30734] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/06/2022] [Accepted: 03/11/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Xiaolin Jin
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
| | - Junjun Liu
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
| | - Shuo Wang
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
| | - Jiale Shi
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
| | - Chengtian Zhao
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
- Sars‐Fang Centre, Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences Ocean University of China Qingdao China
| | - Haibo Xie
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
- Sars‐Fang Centre, Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences Ocean University of China Qingdao China
| | - Yunsi Kang
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
- Sars‐Fang Centre, Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences Ocean University of China Qingdao China
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7
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Haeussler S, Yeroslaviz A, Rolland SG, Luehr S, Lambie EJ, Conradt B. Genome-wide RNAi screen for regulators of UPRmt in Caenorhabditis elegans mutants with defects in mitochondrial fusion. G3-GENES GENOMES GENETICS 2021; 11:6204483. [PMID: 33784383 PMCID: PMC8495942 DOI: 10.1093/g3journal/jkab095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 03/18/2021] [Indexed: 01/22/2023]
Abstract
Mitochondrial dynamics plays an important role in mitochondrial quality control and the adaptation of metabolic activity in response to environmental changes. The disruption of mitochondrial dynamics has detrimental consequences for mitochondrial and cellular homeostasis and leads to the activation of the mitochondrial unfolded protein response (UPRmt), a quality control mechanism that adjusts cellular metabolism and restores homeostasis. To identify genes involved in the induction of UPRmt in response to a block in mitochondrial fusion, we performed a genome-wide RNAi screen in Caenorhabditis elegans mutants lacking the gene fzo-1, which encodes the ortholog of mammalian Mitofusin, and identified 299 suppressors and 86 enhancers. Approximately 90% of these 385 genes are conserved in humans, and one third of the conserved genes have been implicated in human disease. Furthermore, many have roles in developmental processes, which suggests that mitochondrial function and the response to stress are defined during development and maintained throughout life. Our dataset primarily contains mitochondrial enhancers and non-mitochondrial suppressors of UPRmt, indicating that the maintenance of mitochondrial homeostasis has evolved as a critical cellular function, which, when disrupted, can be compensated for by many different cellular processes. Analysis of the subsets 'non-mitochondrial enhancers' and 'mitochondrial suppressors' suggests that organellar contact sites, especially between the ER and mitochondria, are of importance for mitochondrial homeostasis. In addition, we identified several genes involved in IP3 signaling that modulate UPRmt in fzo-1 mutants and found a potential link between pre-mRNA splicing and UPRmt activation.
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Affiliation(s)
- Simon Haeussler
- Faculty of Biology, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Assa Yeroslaviz
- Computational Biology Group, Max Planck Institute of Biochemistry, 82152 Planegg-Martinsried, Germany
| | - Stéphane G Rolland
- Faculty of Biology, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany.,Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, South Korea
| | - Sebastian Luehr
- Faculty of Biology, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Eric J Lambie
- Center for Integrated Protein Science, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Barbara Conradt
- Faculty of Biology, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany.,Center for Integrated Protein Science, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany.,Research Department of Cell and Developmental Biology, Division of Biosciences, University College London, London WC1E 6AP, United Kingdom
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8
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Cherian JR, Adams KV, Petrella LN. Wnt Signaling Drives Ectopic Gene Expression and Larval Arrest in the Absence of the Caenorhabditis elegans DREAM Repressor Complex. G3 (BETHESDA, MD.) 2020; 10:863-874. [PMID: 31843805 PMCID: PMC7003081 DOI: 10.1534/g3.119.400850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 12/08/2019] [Indexed: 11/18/2022]
Abstract
Establishment and maintenance of proper gene expression is a requirement for normal growth and development. The DREAM complex in Caenorhabditis elegans functions as a transcriptional repressor of germline genes in somatic cells. At 26°, DREAM complex mutants show increased misexpression of germline genes in somatic cells and High Temperature Arrest (HTA) of worms at the first larval stage. To identify transcription factors required for the ectopic expression of germline genes in DREAM complex mutants, we conducted an RNA interference screen against 123 transcription factors capable of binding DREAM target promoter loci for suppression of the HTA phenotype in lin-54 mutants. We found that knock-down of 15 embryonically expressed transcription factors suppress the HTA phenotype in lin-54 mutants. Five of the transcription factors found in the initial screen have associations with Wnt signaling pathways. In a subsequent RNAi suppression screen of Wnt signaling factors we found that knock-down of the non-canonical Wnt/PCP pathway factors vang-1, prkl-1 and fmi-1 in a lin-54 mutant background resulted in strong suppression of the HTA phenotype. Animals mutant for both lin-54 and vang-1 showed almost complete suppression of the HTA phenotype, pgl-1 misexpression, and fertility defects associated with lin-54 single mutants at 26°. We propose a model whereby a set of embryonically expressed transcription factors, and the Wnt/PCP pathway, act opportunistically to activate DREAM complex target genes in somatic cells of DREAM complex mutants at 26°.
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Affiliation(s)
- Jerrin R Cherian
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233
| | - Katherine V Adams
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233
| | - Lisa N Petrella
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233
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9
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Han M, Wei G, McManus CE, Hillier LW, Reinke V. Isolated C. elegans germ nuclei exhibit distinct genomic profiles of histone modification and gene expression. BMC Genomics 2019; 20:500. [PMID: 31208332 PMCID: PMC6580472 DOI: 10.1186/s12864-019-5893-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 06/10/2019] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND The wide variety of specialized permissive and repressive mechanisms by which germ cells regulate developmental gene expression are not well understood genome-wide. Isolation of germ cells with high integrity and purity from living animals is necessary to address these open questions, but no straightforward methods are currently available. RESULTS Here we present an experimental paradigm that permits the isolation of nuclei from C. elegans germ cells at quantities sufficient for genomic analyses. We demonstrate that these nuclei represent a very pure population and are suitable for both transcriptome analysis (RNA-seq) and chromatin immunoprecipitation (ChIP-seq) of histone modifications. From these data, we find unexpected germline- and soma-specific patterns of gene regulation. CONCLUSIONS This new capacity removes a major barrier in the field to dissect gene expression mechanisms in the germ line of C. elegans. Consequent discoveries using this technology will be relevant to conserved regulatory mechanisms across species.
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Affiliation(s)
- Mei Han
- Department of Genetics, Yale University, New Haven, CT 06520 USA
| | - Guifeng Wei
- Developmental Epigenetics, Department of Biochemistry, University of Oxford, Oxford, OX1 3QU UK
| | | | - LaDeana W. Hillier
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington, 98195 USA
| | - Valerie Reinke
- Department of Genetics, Yale University, New Haven, CT 06520 USA
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10
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Developmental Control of the Cell Cycle: Insights from Caenorhabditis elegans. Genetics 2019; 211:797-829. [PMID: 30846544 PMCID: PMC6404260 DOI: 10.1534/genetics.118.301643] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 10/10/2018] [Indexed: 12/11/2022] Open
Abstract
During animal development, a single fertilized egg forms a complete organism with tens to trillions of cells that encompass a large variety of cell types. Cell cycle regulation is therefore at the center of development and needs to be carried out in close coordination with cell differentiation, migration, and death, as well as tissue formation, morphogenesis, and homeostasis. The timing and frequency of cell divisions are controlled by complex combinations of external and cell-intrinsic signals that vary throughout development. Insight into how such controls determine in vivo cell division patterns has come from studies in various genetic model systems. The nematode Caenorhabditis elegans has only about 1000 somatic cells and approximately twice as many germ cells in the adult hermaphrodite. Despite the relatively small number of cells, C. elegans has diverse tissues, including intestine, nerves, striated and smooth muscle, and skin. C. elegans is unique as a model organism for studies of the cell cycle because the somatic cell lineage is invariant. Somatic cells divide at set times during development to produce daughter cells that adopt reproducible developmental fates. Studies in C. elegans have allowed the identification of conserved cell cycle regulators and provided insights into how cell cycle regulation varies between tissues. In this review, we focus on the regulation of the cell cycle in the context of C. elegans development, with reference to other systems, with the goal of better understanding how cell cycle regulation is linked to animal development in general.
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11
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Tzur YB, Winter E, Gao J, Hashimshony T, Yanai I, Colaiácovo MP. Spatiotemporal Gene Expression Analysis of the Caenorhabditis elegans Germline Uncovers a Syncytial Expression Switch. Genetics 2018; 210:587-605. [PMID: 30093412 PMCID: PMC6216576 DOI: 10.1534/genetics.118.301315] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 08/03/2018] [Indexed: 11/18/2022] Open
Abstract
Developmental programs are executed by tightly controlled gene regulatory pathways. Here, we combined the unique sample retrieval capacity afforded by laser capture microscopy with analysis of mRNA abundance by CEL-Seq (cell expression by linear amplification and sequencing) to generate a spatiotemporal gene expression map of the Caenorhabditis elegans syncytial germline from adult hermaphrodites and males. We found that over 6000 genes exhibit spatiotemporally dynamic expression patterns throughout the hermaphrodite germline, with two dominant groups of genes exhibiting reciprocal shifts in expression at late pachytene during meiotic prophase I. We found a strong correlation between restricted spatiotemporal expression and known developmental and cellular processes, indicating that these gene expression changes may be an important driver of germ cell progression. Analysis of the male gonad revealed a shift in gene expression at early pachytene and upregulation of subsets of genes following the meiotic divisions, specifically in early and late spermatids, mostly transcribed from the X chromosome. We observed that while the X chromosome is silenced throughout the first half of the gonad, some genes escape this control and are highly expressed throughout the germline. Although we found a strong correlation between the expression of genes corresponding to CSR-1-interacting 22G-RNAs during germ cell progression, we also found that a large fraction of genes may bypass the need for CSR-1-mediated germline licensing. Taken together, these findings suggest the existence of mechanisms that enable a shift in gene expression during prophase I to promote germ cell progression.
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Affiliation(s)
- Yonatan B Tzur
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
- Department of Genetics, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem 91904, Israel
| | - Eitan Winter
- Department of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Jinmin Gao
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Tamar Hashimshony
- Department of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Itai Yanai
- Department of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel
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12
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Furuta T, Joo HJ, Trimmer KA, Chen SY, Arur S. GSK-3 promotes S-phase entry and progression in C. elegans germline stem cells to maintain tissue output. Development 2018; 145:dev.161042. [PMID: 29695611 DOI: 10.1242/dev.161042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 04/17/2018] [Indexed: 12/26/2022]
Abstract
Adult C. elegans germline stem cells (GSCs) and mouse embryonic stem cells (mESCs) exhibit a non-canonical cell cycle structure with an abbreviated G1 phase and phase-independent expression of Cdk2 and cyclin E. Mechanisms that promote the abbreviated cell cycle remain unknown, as do the consequences of not maintaining an abbreviated cell cycle in these tissues. In GSCs, we discovered that loss of gsk-3 results in reduced GSC proliferation without changes in differentiation or responsiveness to GLP-1/Notch signaling. We find that DPL-1 transcriptional activity inhibits CDK-2 mRNA accumulation in GSCs, which leads to slower S-phase entry and progression. Inhibition of dpl-1 or transgenic expression of CDK-2 via a heterologous germline promoter rescues the S-phase entry and progression defects of the gsk-3 mutants, demonstrating that transcriptional regulation rather than post-translational control of CDK-2 establishes the abbreviated cell cycle structure in GSCs. This highlights an inhibitory cascade wherein GSK-3 inhibits DPL-1 and DPL-1 inhibits cdk-2 transcription. Constitutive GSK-3 activity through this cascade maintains an abbreviated cell cycle structure to permit the efficient proliferation of GSCs necessary for continuous tissue output.
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Affiliation(s)
- Tokiko Furuta
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Hyoe-Jin Joo
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Kenneth A Trimmer
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.,Genes and Development Graduate Program, MD Anderson Cancer Center UT Health Graduate School of Biomedical Sciences, Houston, TX 77030, USA
| | - Shin-Yu Chen
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Swathi Arur
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA .,Genes and Development Graduate Program, MD Anderson Cancer Center UT Health Graduate School of Biomedical Sciences, Houston, TX 77030, USA
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13
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Goetsch PD, Garrigues JM, Strome S. Loss of the Caenorhabditis elegans pocket protein LIN-35 reveals MuvB's innate function as the repressor of DREAM target genes. PLoS Genet 2017; 13:e1007088. [PMID: 29091720 PMCID: PMC5683655 DOI: 10.1371/journal.pgen.1007088] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 11/13/2017] [Accepted: 10/24/2017] [Indexed: 12/27/2022] Open
Abstract
The DREAM (Dp/Retinoblastoma(Rb)-like/E2F/MuvB) transcriptional repressor complex acts as a gatekeeper of the mammalian cell cycle by establishing and maintaining cellular quiescence. How DREAM’s three functional components, the E2F-DP heterodimer, the Rb-like pocket protein, and the MuvB subcomplex, form and function at target gene promoters remains unknown. The current model invokes that the pocket protein links E2F-DP and MuvB and is essential for gene repression. We tested this model by assessing how the conserved yet less redundant DREAM system in Caenorhabditis elegans is affected by absence of the sole C. elegans pocket protein LIN-35. Using a LIN-35 protein null mutant, we analyzed the assembly of E2F-DP and MuvB at promoters that are bound by DREAM and the level of expression of those "DREAM target genes" in embryos. We report that LIN-35 indeed mediates the association of E2F-DP and MuvB, a function that stabilizes DREAM subunit occupancy at target genes. In the absence of LIN-35, the occupancy of E2F-DP and MuvB at most DREAM target genes decreases dramatically and many of those genes become upregulated. The retention of E2F-DP and MuvB at some target gene promoters in lin-35 null embryos allowed us to test their contribution to DREAM target gene repression. Depletion of MuvB, but not E2F-DP, in the sensitized lin-35 null background caused further upregulation of DREAM target genes. We conclude that the pocket protein functions primarily to support MuvB-mediated repression of DREAM targets and that transcriptional repression is the innate function of the evolutionarily conserved MuvB complex. Our findings provide important insights into how mammalian DREAM assembly and disassembly may regulate gene expression and the cell cycle. The 8-subunit DREAM transcriptional repressor complex contains 3 functional components that together control expression of cell cycle and developmental genes. How the E2F-DP transcription factor heterodimer, the pocket protein, and the highly conserved MuvB complex coalesce on chromatin and repress DREAM target genes has yet to be determined. We directly tested the prevailing model that the DREAM pocket protein links E2F-DP to MuvB and is required for gene repression. Using a protein null mutant of the sole C. elegans pocket protein LIN-35, we demonstrate that the pocket protein indeed links E2F-DP and MuvB, which aids in the stable occupancy of DREAM components near target genes. Depletion of additional DREAM components in lin-35 null worms revealed that the remaining chromatin-bound MuvB represses target genes. We conclude that the MuvB subcomplex mediates DREAM’s critical repressive function. Our functional genomics approach in the simplified C. elegans system reveals that the ancestral function of the pocket protein is to stabilize the innate repressive activity of MuvB, ensuring proper regulation of DREAM target genes through development.
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Affiliation(s)
- Paul D. Goetsch
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Jacob M. Garrigues
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Susan Strome
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, United States of America
- * E-mail:
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14
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Abstract
The E2F family of transcription factors is a key determinant of cell proliferation in response to extra- and intra-cellular signals. Within this family, E2F4 is a transcriptional repressor whose activity is critical to engage and maintain cell cycle arrest in G0/G1 in conjunction with members of the retinoblastoma (RB) family. However, recent observations challenge this paradigm and indicate that E2F4 has a multitude of functions in cells besides this cell cycle regulatory role, including in embryonic and adult stem cells, during regenerative processes, and in cancer. Some of these new functions are independent of the RB family and involve direct activation of target genes. Here we review the canonical functions of E2F4 and discuss recent evidence expanding the role of this transcription factor, with a focus on cell fate decisions in tissue homeostasis and regeneration.
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Affiliation(s)
- Jenny Hsu
- a Departments of Pediatrics and Genetics , Stanford University , Stanford , CA , USA
| | - Julien Sage
- a Departments of Pediatrics and Genetics , Stanford University , Stanford , CA , USA
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15
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Li J, Chauve L, Phelps G, Brielmann RM, Morimoto RI. E2F coregulates an essential HSF developmental program that is distinct from the heat-shock response. Genes Dev 2016; 30:2062-2075. [PMID: 27688402 PMCID: PMC5066613 DOI: 10.1101/gad.283317.116] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 09/06/2016] [Indexed: 01/08/2023]
Abstract
Heat-shock factor (HSF) is the master transcriptional regulator of the heat-shock response (HSR) and is essential for stress resilience. HSF is also required for metazoan development; however, its function and regulation in this process are poorly understood. Here, we characterize the genomic distribution and transcriptional activity of Caenorhabditis elegans HSF-1 during larval development and show that the developmental HSF-1 transcriptional program is distinct from the HSR. HSF-1 developmental activation requires binding of E2F/DP to a GC-rich motif that facilitates HSF-1 binding to a heat-shock element (HSE) that is degenerate from the consensus HSE sequence and adjacent to the E2F-binding site at promoters. In contrast, induction of the HSR is independent of these promoter elements or E2F/DP and instead requires a distinct set of tandem canonical HSEs. Together, E2F and HSF-1 directly regulate a gene network, including a specific subset of chaperones, to promote protein biogenesis and anabolic metabolism, which are essential in development.
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Affiliation(s)
- Jian Li
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, Illinois 60208, USA
| | - Laetitia Chauve
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, Illinois 60208, USA
| | - Grace Phelps
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, Illinois 60208, USA
| | - Renée M Brielmann
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, Illinois 60208, USA
| | - Richard I Morimoto
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, Illinois 60208, USA
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16
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Regulation of cell polarity determinants by the Retinoblastoma tumor suppressor protein. Sci Rep 2016; 6:22879. [PMID: 26971715 PMCID: PMC4789731 DOI: 10.1038/srep22879] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 02/23/2016] [Indexed: 01/24/2023] Open
Abstract
In addition to their canonical roles in the cell cycle, RB family proteins regulate numerous developmental pathways, although the mechanisms remain obscure. We found that Drosophila Rbf1 associates with genes encoding components of the highly conserved apical-basal and planar cell polarity pathways, suggesting a possible regulatory role. Here, we show that depletion of Rbf1 in Drosophila tissues is indeed associated with polarity defects in the wing and eye. Key polarity genes aPKC, par6, vang, pk, and fmi are upregulated, and an aPKC mutation suppresses the Rbf1-induced phenotypes. RB control of cell polarity may be an evolutionarily conserved function, with important implications in cancer metastasis.
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17
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The E2F-DP1 Transcription Factor Complex Regulates Centriole Duplication in Caenorhabditis elegans. G3-GENES GENOMES GENETICS 2016; 6:709-20. [PMID: 26772748 PMCID: PMC4777132 DOI: 10.1534/g3.115.025577] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Centrioles play critical roles in the organization of microtubule-based structures, from the mitotic spindle to cilia and flagella. In order to properly execute their various functions, centrioles are subjected to stringent copy number control. Central to this control mechanism is a precise duplication event that takes place during S phase of the cell cycle and involves the assembly of a single daughter centriole in association with each mother centriole . Recent studies have revealed that posttranslational control of the master regulator Plk4/ZYG-1 kinase and its downstream effector SAS-6 is key to ensuring production of a single daughter centriole. In contrast, relatively little is known about how centriole duplication is regulated at a transcriptional level. Here we show that the transcription factor complex EFL-1-DPL-1 both positively and negatively controls centriole duplication in the Caenorhabditis elegans embryo. Specifically, we find that down regulation of EFL-1-DPL-1 can restore centriole duplication in a zyg-1 hypomorphic mutant and that suppression of the zyg-1 mutant phenotype is accompanied by an increase in SAS-6 protein levels. Further, we find evidence that EFL-1-DPL-1 promotes the transcription of zyg-1 and other centriole duplication genes. Our results provide evidence that in a single tissue type, EFL-1-DPL-1 sets the balance between positive and negative regulators of centriole assembly and thus may be part of a homeostatic mechanism that governs centriole assembly.
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Noble DC, Aoki ST, Ortiz MA, Kim KW, Verheyden JM, Kimble J. Genomic Analyses of Sperm Fate Regulator Targets Reveal a Common Set of Oogenic mRNAs in Caenorhabditis elegans. Genetics 2016; 202:221-34. [PMID: 26564160 PMCID: PMC4701086 DOI: 10.1534/genetics.115.182592] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 11/03/2015] [Indexed: 12/18/2022] Open
Abstract
Germ cell specification as sperm or oocyte is an ancient cell fate decision, but its molecular regulation is poorly understood. In Caenorhabditis elegans, the FOG-1 and FOG-3 proteins behave genetically as terminal regulators of sperm fate specification. Both are homologous to well-established RNA regulators, suggesting that FOG-1 and FOG-3 specify the sperm fate post-transcriptionally. We predicted that FOG-1 and FOG-3, as terminal regulators of the sperm fate, might regulate a battery of gamete-specific differentiation genes. Here we test that prediction by exploring on a genomic scale the messenger RNAs (mRNAs) associated with FOG-1 and FOG-3. Immunoprecipitation of the proteins and their associated mRNAs from spermatogenic germlines identifies 81 FOG-1 and 722 FOG-3 putative targets. Importantly, almost all FOG-1 targets are also FOG-3 targets, and these common targets are strongly biased for oogenic mRNAs. The discovery of common target mRNAs suggested that FOG-1 and FOG-3 work together. Consistent with that idea, we find that FOG-1 and FOG-3 proteins co-immunoprecipitate from both intact nematodes and mammalian tissue culture cells and that they colocalize in germ cells. Taking our results together, we propose a model in which FOG-1 and FOG-3 work in a complex to repress oogenic transcripts and thereby promote the sperm fate.
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Affiliation(s)
- Daniel C Noble
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Scott T Aoki
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Marco A Ortiz
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Kyung Won Kim
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Jamie M Verheyden
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Judith Kimble
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706 Howard Hughes Medical Institute, University of Wisconsin, Madison, Wisconsin 53706
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19
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Zhou K, Huang B, Zou M, Lu D, He S, Wang G. Genome-wide identification of lineage-specific genes within Caenorhabditis elegans. Genomics 2015; 106:242-8. [PMID: 26188256 DOI: 10.1016/j.ygeno.2015.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 07/08/2015] [Accepted: 07/09/2015] [Indexed: 11/19/2022]
Abstract
With the rapid growth of sequencing technology, a number of genomes and transcriptomes of various species have been sequenced, contributing to the study of lineage-specific genes (LSGs). We identified two sets of LSGs using BLAST: one included Caenorhabditis elegans species-specific genes (1423, SSGs), and the other consisted of Caenorhabditis genus-specific genes (4539, GSGs). The subsequent characterization and analysis of the SSGs and GSGs showed that they have significant differences in evolution and that most LSGs were generated by gene duplication and integration of transposable elements (TEs). We then performed temporal expression profiling and protein function prediction and observed that many SSGs and GSGs are expressed and that genes involved with sex determination, specific stress, immune response, and morphogenesis are over-represented, suggesting that these specific genes may be related to the Caenorhabditis nematodes' special ability to survive in severe and extreme environments.
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Affiliation(s)
- Kun Zhou
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, China.
| | - Beibei Huang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, China.
| | - Ming Zou
- Huazhong Agriculture University, Wuhan 430070, China.
| | - Dandan Lu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, China.
| | - Shunping He
- The Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
| | - Guoxiu Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, China.
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20
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Lipidomic and proteomic analysis of Caenorhabditis elegans lipid droplets and identification of ACS-4 as a lipid droplet-associated protein. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1337-45. [PMID: 26121959 DOI: 10.1016/j.bbalip.2015.06.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 06/08/2015] [Accepted: 06/25/2015] [Indexed: 01/08/2023]
Abstract
Lipid droplets are cytoplasmic organelles that store neutral lipids for membrane synthesis and energy reserves. In this study, we characterized the lipid and protein composition of purified Caenorhabditis elegans lipid droplets. These lipid droplets are composed mainly of triacylglycerols, surrounded by a phospholipid monolayer composed primarily of phosphatidylcholine and phosphatidylethanolamine. The fatty acid composition of the triacylglycerols is rich in fatty acid species obtained from the dietary Escherichia coli, including cyclopropane fatty acids and cis-vaccenic acid. Unlike other organisms, C. elegans lipid droplets contain very little cholesterol or cholesterol esters. Comparison of the lipid droplet proteomes of wild type and high-fat daf-2 mutant strains shows a very similar proteome in both strains, except that the most abundant protein in the C. elegans lipid droplet proteome, MDT-28, is relatively less abundant in lipid droplets isolated from daf-2 mutants. Functional analysis of lipid droplet proteins identified in our proteomic studies indicated an enrichment of proteins required for growth and fat homeostasis in C. elegans. Finally, we confirmed the localization of one of the newly identified lipid droplet proteins, ACS-4. We found that ACS-4 localizes to the surface of lipid droplets in the C. elegans intestine and skin. This study bolsters C. elegans as a model to study the dynamics and functions of lipid droplets in a multicellular organism.
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A Forward Genetic Screen for Suppressors of Somatic P Granules in Caenorhabditis elegans. G3-GENES GENOMES GENETICS 2015; 5:2209-15. [PMID: 26100681 PMCID: PMC4593002 DOI: 10.1534/g3.115.019257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In Caenorhabditis elegans, germline expression programs are actively repressed in somatic tissue by components of the synMuv (synthetic multi-vulva) B chromatin remodeling complex, which include homologs of tumor suppressors Retinoblastoma (Rb/LIN-35) and Malignant Brain Tumor (MBT/LIN-61). However, the full scope of pathways that suppress germline expression in the soma is unknown. To address this, we performed a mutagenesis and screened for somatic expression of GFP-tagged PGL-1, a core P-granule nucleating protein. Eight alleles were isolated from 4000 haploid genomes. Five of these alleles exhibit a synMuv phenotype, whereas the remaining three were identified as hypomorphic alleles of known synMuv B genes, lin-13 and dpl-1. These findings suggest that most suppressors of germline programs in the soma of C. elegans are either required for viability or function through synMuv B chromatin regulation.
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22
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Latorre I, Chesney MA, Garrigues JM, Stempor P, Appert A, Francesconi M, Strome S, Ahringer J. The DREAM complex promotes gene body H2A.Z for target repression. Genes Dev 2015; 29:495-500. [PMID: 25737279 PMCID: PMC4358402 DOI: 10.1101/gad.255810.114] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The DREAM (DP, Retinoblastoma [Rb]-like, E2F, and MuvB) complex controls cellular quiescence by repressing cell cycle genes. Latorre et al. show that Caenorhabditis elegans DREAM targets have an unusual pattern of high gene body HTZ-1/H2A.Z. In mutants of lin-35, the sole p130/Rb-like gene in C. elegans, DREAM targets have reduced gene body HTZ-1/H2A.Z and increased expression. Consistent with a repressive role for gene body H2A.Z, many DREAM targets are up-regulated in htz-1/H2A.Z mutants. The DREAM (DP, Retinoblastoma [Rb]-like, E2F, and MuvB) complex controls cellular quiescence by repressing cell cycle genes, but its mechanism of action is poorly understood. Here we show that Caenorhabditis elegans DREAM targets have an unusual pattern of high gene body HTZ-1/H2A.Z. In mutants of lin-35, the sole p130/Rb-like gene in C. elegans, DREAM targets have reduced gene body HTZ-1/H2A.Z and increased expression. Consistent with a repressive role for gene body H2A.Z, many DREAM targets are up-regulated in htz-1/H2A.Z mutants. Our results indicate that the DREAM complex facilitates high gene body HTZ-1/H2A.Z, which plays a role in target gene repression.
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Affiliation(s)
- Isabel Latorre
- The Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, United Kingdom
| | - Michael A Chesney
- The Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, United Kingdom
| | - Jacob M Garrigues
- Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, California 95064, USA
| | - Przemyslaw Stempor
- The Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, United Kingdom
| | - Alex Appert
- The Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, United Kingdom
| | - Mirko Francesconi
- EMBL-CRG Systems Biology Unit, Centre for Genomic Regulation (CRG), Universitat Pompeu Fabra (UPF), Barcelona 08003, Spain
| | - Susan Strome
- Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, California 95064, USA
| | - Julie Ahringer
- The Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, United Kingdom;
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LIN-35/Rb causes starvation-induced germ cell apoptosis via CED-9/Bcl2 downregulation in Caenorhabditis elegans. Mol Cell Biol 2014; 34:2499-516. [PMID: 24752899 DOI: 10.1128/mcb.01532-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Apoptosis is an important mechanism for maintaining germ line health. In Caenorhabditis elegans, germ cell apoptosis occurs under normal conditions to sustain gonad homeostasis and oocyte quality. Under stress, germ cell apoptosis can be triggered via different pathways, including the following: (i) the CEP-1/p53 pathway, which induces germ cell apoptosis when animals are exposed to DNA damage; (ii) the mitogen-activated protein kinase kinase (MAPKK) pathway, which triggers germ cell apoptosis when animals are exposed to heat shock, oxidative stress, or osmotic stress; and (iii) an unknown mechanism that triggers germ cell apoptosis during starvation. Here, we address how starvation induces germ cell apoptosis. Using polysomal profiling, we found that starvation for 6 h reduces the translationally active ribosomes, which differentially affect the mRNAs of the core apoptotic machinery and some of its regulators. During starvation, lin-35/Rb mRNA increases its expression, resulting in the accumulation of this protein. As a consequence, LIN-35 downregulates the expression of the antiapoptotic gene ced-9/Bcl-2. We observed that the reduced translation of ced-9/Bcl-2 mRNA during food deprivation together with its downregulation drastically affects its protein accumulation. We propose that CED-9/Bcl-2 downregulation via LIN-35/Rb triggers germ cell apoptosis in C. elegans in response to starvation.
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24
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Opposing activities of DRM and MES-4 tune gene expression and X-chromosome repression in Caenorhabditis elegans germ cells. G3-GENES GENOMES GENETICS 2014; 4:143-53. [PMID: 24281426 PMCID: PMC3887530 DOI: 10.1534/g3.113.007849] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During animal development, gene transcription is tuned to tissue-appropriate levels. Here we uncover antagonistic regulation of transcript levels in the germline of Caenorhabditis elegans hermaphrodites. The histone methyltransferase MES-4 (Maternal Effect Sterile-4) marks genes expressed in the germline with methylated lysine on histone H3 (H3K36me) and promotes their transcription; MES-4 also represses genes normally expressed in somatic cells and genes on the X chromosome. The DRM transcription factor complex, named for its Dp/E2F, Retinoblastoma-like, and MuvB subunits, affects germline gene expression and prevents excessive repression of X-chromosome genes. Using genome-scale analyses of germline tissue, we show that common germline-expressed genes are activated by MES-4 and repressed by DRM, and that MES-4 and DRM co-bind many germline-expressed genes. Reciprocally, MES-4 represses and DRM activates a set of autosomal soma-expressed genes and overall X-chromosome gene expression. Mutations in mes-4 and the DRM subunit lin-54 oppositely skew the transcript levels of their common targets and cause sterility. A double mutant restores target gene transcript levels closer to wild type, and the concomitant loss of lin-54 suppresses the severe germline proliferation defect observed in mes-4 single mutants. Together, “yin-yang” regulation by MES-4 and DRM ensures transcript levels appropriate for germ-cell function, elicits robust but not excessive dampening of X-chromosome-wide transcription, and may poise genes for future expression changes. Our study reveals that conserved transcriptional regulators implicated in development and cancer counteract each other to fine-tune transcript dosage.
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Huang X, Chen L, Chim H, Chan LLH, Zhao Z, Yan H. Boolean genetic network model for the control of C. elegans early embryonic cell cycles. Biomed Eng Online 2013; 12 Suppl 1:S1. [PMID: 24564942 PMCID: PMC4029147 DOI: 10.1186/1475-925x-12-s1-s1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Background In Caenorhabditis elegans early embryo, cell cycles only have two phases: DNA synthesis and mitosis, which are different from the typical 4-phase cell cycle. Modeling this cell-cycle process into network can fill up the gap in C. elegans cell-cycle study and provide a thorough understanding on the cell-cycle regulations and progressions at the network level. Methods In this paper, C. elegans early embryonic cell-cycle network has been constructed based on the knowledge of key regulators and their interactions from literature studies. A discrete dynamical Boolean model has been applied in computer simulations to study dynamical properties of this network. The cell-cycle network is compared with random networks and tested under several perturbations to analyze its robustness. To investigate whether our proposed network could explain biological experiment results, we have also compared the network simulation results with gene knock down experiment data. Results With the Boolean model, this study showed that the cell-cycle network was stable with a set of attractors (fixed points). A biological pathway was observed in the simulation, which corresponded to a whole cell-cycle progression. The C. elegans network was significantly robust when compared with random networks of the same size because there were less attractors and larger basins than random networks. Moreover, the network was also robust under perturbations with no significant change of the basin size. In addition, the smaller number of attractors and the shorter biological pathway from gene knock down network simulation interpreted the shorter cell-cycle lengths in mutant from the RNAi gene knock down experiment data. Hence, we demonstrated that the results in network simulation could be verified by the RNAi gene knock down experiment data. Conclusions A C. elegans early embryonic cell cycles network was constructed and its properties were analyzed and compared with those of random networks. Computer simulation results provided biologically meaningful interpretations of RNAi gene knock down experiment data.
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26
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Tissue-specific direct targets of Caenorhabditis elegans Rb/E2F dictate distinct somatic and germline programs. Genome Biol 2013; 14:R5. [PMID: 23347407 PMCID: PMC4053757 DOI: 10.1186/gb-2013-14-1-r5] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 01/23/2013] [Indexed: 01/12/2023] Open
Abstract
Background The tumor suppressor Rb/E2F regulates gene expression to control differentiation in multiple tissues during development, although how it directs tissue-specific gene regulation in vivo is poorly understood. Results We determined the genome-wide binding profiles for Caenorhabditis elegans Rb/E2F-like components in the germline, in the intestine and broadly throughout the soma, and uncovered highly tissue-specific binding patterns and target genes. Chromatin association by LIN-35, the C. elegans ortholog of Rb, is impaired in the germline but robust in the soma, a characteristic that might govern differential effects on gene expression in the two cell types. In the intestine, LIN-35 and the heterochromatin protein HPL-2, the ortholog of Hp1, coordinately bind at many sites lacking E2F. Finally, selected direct target genes contribute to the soma-to-germline transformation of lin-35 mutants, including mes-4, a soma-specific target that promotes H3K36 methylation, and csr-1, a germline-specific target that functions in a 22G small RNA pathway. Conclusions In sum, identification of tissue-specific binding profiles and effector target genes reveals important insights into the mechanisms by which Rb/E2F controls distinct cell fates in vivo.
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27
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Control of oocyte growth and meiotic maturation in Caenorhabditis elegans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 757:277-320. [PMID: 22872481 DOI: 10.1007/978-1-4614-4015-4_10] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In sexually reproducing animals, oocytes arrest at diplotene or diakinesis and resume meiosis (meiotic maturation) in response to hormones. Chromosome segregation errors in female meiosis I are the leading cause of human birth defects, and age-related changes in the hormonal environment of the ovary are a suggested cause. Caenorhabditis elegans is emerging as a genetic paradigm for studying hormonal control of meiotic maturation. The meiotic maturation processes in C. elegans and mammals share a number of biological and molecular similarities. Major sperm protein (MSP) and luteinizing hormone (LH), though unrelated in sequence, both trigger meiotic resumption using somatic Gα(s)-adenylate cyclase pathways and soma-germline gap-junctional communication. At a molecular level, the oocyte responses apparently involve the control of conserved protein kinase pathways and post-transcriptional gene regulation in the oocyte. At a cellular level, the responses include cortical cytoskeletal rearrangement, nuclear envelope breakdown, assembly of the acentriolar meiotic spindle, chromosome segregation, and likely changes important for fertilization and the oocyte-to-embryo transition. This chapter focuses on signaling mechanisms required for oocyte growth and meiotic maturation in C. elegans and discusses how these mechanisms coordinate the completion of meiosis and the oocyte-to-embryo transition.
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28
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The Retinoblastoma pathway regulates stem cell proliferation in freshwater planarians. Dev Biol 2012; 373:442-52. [PMID: 23123964 DOI: 10.1016/j.ydbio.2012.10.025] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 10/16/2012] [Accepted: 10/22/2012] [Indexed: 02/01/2023]
Abstract
Freshwater planarians are flatworms of the Lophotrochozoan superphylum and are well known for their regenerative abilities, which rely on a large population of pluripotent adult stem cells. However, the mechanisms by which planarians maintain a precise population of adult stem cells while balancing proliferation and cell death, remain to be elucidated. Here we have identified, characterized, and functionally tested the core Retinoblastoma (Rb) pathway components in planarian adult stem cell biology. The Rb pathway is an ancient and conserved mechanism of proliferation control from plants to animals and is composed of three core components: an Rb protein, and a transcription factor heterodimer of E2F and DP proteins. Although the planarian genome contains all components of the Rb pathway, we found that they have undergone gene loss from the ancestral state, similar to other species in their phylum. The single Rb homolog (Smed-Rb) was highly expressed in planarian stem cells and was required for stem cell maintenance, similar to the Rb-homologs p107 and p130 in vertebrates. We show that planarians and their phylum have undergone the most severe reduction in E2F genes observed thus far, and the single remaining E2F was predicted to be a repressive-type E2F (Smed-E2F4-1). Knockdown of either Smed-E2F4-1 or its dimerization partner Dp (Smed-Dp) by RNAi resulted in temporary hyper-proliferation. Finally, we showed that known Rb-interacting genes in other systems, histone deacetylase 1 and cyclinD (Smed-HDAC1; Smed-cycD), were similar to Rb in expression and phenotypes when knocked down by RNAi, suggesting that these established interactions with Rb may also be conserved in planarians. Together, these results showed that planarians use the conserved components of the Rb tumor suppressor pathway to control proliferation and cell survival.
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Miedel MT, Graf NJ, Stephen KE, Long OS, Pak SC, Perlmutter DH, Silverman GA, Luke CJ. A pro-cathepsin L mutant is a luminal substrate for endoplasmic-reticulum-associated degradation in C. elegans. PLoS One 2012; 7:e40145. [PMID: 22768338 PMCID: PMC3388072 DOI: 10.1371/journal.pone.0040145] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 06/01/2012] [Indexed: 11/29/2022] Open
Abstract
Endoplasmic-reticulum associated degradation (ERAD) is a major cellular misfolded protein disposal pathway that is well conserved from yeast to mammals. In yeast, a mutant of carboxypeptidase Y (CPY*) was found to be a luminal ER substrate and has served as a useful marker to help identify modifiers of the ERAD pathway. Due to its ease of genetic manipulation and the ability to conduct a genome wide screen for modifiers of molecular pathways, C. elegans has become one of the preferred metazoans for studying cell biological processes, such as ERAD. However, a marker of ERAD activity comparable to CPY* has not been developed for this model system. We describe a mutant of pro-cathepsin L fused to YFP that no longer targets to the lysosome, but is efficiently eliminated by the ERAD pathway. Using this mutant pro-cathepsin L, we found that components of the mammalian ERAD system that participate in the degradation of ER luminal substrates were conserved in C. elegans. This transgenic line will facilitate high-throughput genetic or pharmacological screens for ERAD modifiers using widefield epifluorescence microscopy.
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Affiliation(s)
- Mark T. Miedel
- Department of Pediatrics, Cell Biology and Physiology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee-Womens Hospital of UPMC, Pittsburgh, Pennsylvania, United States of America
| | - Nathan J. Graf
- Department of Pediatrics, Cell Biology and Physiology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee-Womens Hospital of UPMC, Pittsburgh, Pennsylvania, United States of America
| | - Kate E. Stephen
- Department of Pediatrics, Cell Biology and Physiology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee-Womens Hospital of UPMC, Pittsburgh, Pennsylvania, United States of America
| | - Olivia S. Long
- Department of Pediatrics, Cell Biology and Physiology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee-Womens Hospital of UPMC, Pittsburgh, Pennsylvania, United States of America
| | - Stephen C. Pak
- Department of Pediatrics, Cell Biology and Physiology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee-Womens Hospital of UPMC, Pittsburgh, Pennsylvania, United States of America
| | - David H. Perlmutter
- Department of Pediatrics, Cell Biology and Physiology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee-Womens Hospital of UPMC, Pittsburgh, Pennsylvania, United States of America
| | - Gary A. Silverman
- Department of Pediatrics, Cell Biology and Physiology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee-Womens Hospital of UPMC, Pittsburgh, Pennsylvania, United States of America
| | - Cliff J. Luke
- Department of Pediatrics, Cell Biology and Physiology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee-Womens Hospital of UPMC, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Abstract
The Caenorhabditis elegans pRb ortholog, LIN-35, functions in a wide range of cellular and developmental processes. This includes a role of LIN-35 in nutrient utilization by the intestine, which it carries out redundantly with SLR-2, a zinc-finger protein. This and other redundant functions of LIN-35 were identified in genetic screens for mutations that display synthetic phenotypes in conjunction with loss of lin-35. To explore the intestinal role of LIN-35, we conducted a genome-wide RNA-interference-feeding screen for suppressors of lin-35; slr-2 early larval arrest. Of the 26 suppressors identified, 17 fall into three functional classes: (1) ribosome biogenesis genes, (2) mitochondrial prohibitins, and (3) chromatin regulators. Further characterization indicates that different categories of suppressors act through distinct molecular mechanisms. We also tested lin-35; slr-2 suppressors, as well as suppressors of the synthetic multivulval phenotype, to determine the spectrum of lin-35-synthetic phenotypes that could be suppressed following inhibition of these genes. We identified 19 genes, most of which are evolutionarily conserved, that can suppress multiple unrelated lin-35-synthetic phenotypes. Our study reveals a network of genes broadly antagonistic to LIN-35 as well as genes specific to the role of LIN-35 in intestinal and vulval development. Suppressors of multiple lin-35 phenotypes may be candidate targets for anticancer therapies. Moreover, screening for suppressors of phenotypically distinct synthetic interactions, which share a common altered gene, may prove to be a novel and effective approach for identifying genes whose activities are most directly relevant to the core functions of the shared gene.
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C. elegans germ cells show temperature and age-dependent expression of Cer1, a Gypsy/Ty3-related retrotransposon. PLoS Pathog 2012; 8:e1002591. [PMID: 22479180 PMCID: PMC3315495 DOI: 10.1371/journal.ppat.1002591] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 01/30/2012] [Indexed: 11/19/2022] Open
Abstract
Virus-like particles (VLPs) have not been observed in Caenorhabditis germ cells, although nematode genomes contain low numbers of retrotransposon and retroviral sequences. We used electron microscopy to search for VLPs in various wild strains of Caenorhabditis, and observed very rare candidate VLPs in some strains, including the standard laboratory strain of C. elegans, N2. We identified the N2 VLPs as capsids produced by Cer1, a retrotransposon in the Gypsy/Ty3 family of retroviruses/retrotransposons. Cer1 expression is age and temperature dependent, with abundant expression at 15°C and no detectable expression at 25°C, explaining how VLPs escaped detection in previous studies. Similar age and temperature-dependent expression of Cer1 retrotransposons was observed for several other wild strains, indicating that these properties are common, if not integral, features of this retroelement. Retrotransposons, in contrast to DNA transposons, have a cytoplasmic stage in replication, and those that infect non-dividing cells must pass their genomic material through nuclear pores. In most C. elegans germ cells, nuclear pores are largely covered by germline-specific organelles called P granules. Our results suggest that Cer1 capsids target meiotic germ cells exiting pachytene, when free nuclear pores are added to the nuclear envelope and existing P granules begin to be removed. In pachytene germ cells, Cer1 capsids concentrate away from nuclei on a subset of microtubules that are exceptionally resistant to microtubule inhibitors; the capsids can aggregate these stable microtubules in older adults, which exhibit a temperature-dependent decrease in egg viability. When germ cells exit pachytene, the stable microtubules disappear and capsids redistribute close to nuclei that have P granule-free nuclear pores. This redistribution is microtubule dependent, suggesting that capsids that are released from stable microtubules transfer onto new, dynamic microtubules to track toward nuclei. These studies introduce C. elegans as a model to study the interplay between retroelements and germ cell biology. Retrotransposons and retroviruses pose enormous threats to animal and plants because of their ability to insert into host genes. Retroelements that replicate in germ cells can, if left unchecked, expand exponentially in the host genome. C. elegans has proven to be an exceptional model system for studying many facets of cell and molecular biology, and the genome contains both retrotransposon and retroviral sequences. However, no virus-like particles have been observed in C. elegans germ cells. We show here that Cer1, an endogenous Gypsy/Ty3 class retrotransposon, is expressed at very high levels in C. elegans germ cells, but escaped detection in previous studies because its expression is both temperature and age dependent. These studies reveal new aspects of microtubule regulation in C. elegans that the retroelement appears to exploit to navigate the germ cell cytoplasm, and demonstrate the power of C. elegans for studying host/pathogen interactions in germ cell biology.
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Petrella LN, Wang W, Spike CA, Rechtsteiner A, Reinke V, Strome S. synMuv B proteins antagonize germline fate in the intestine and ensure C. elegans survival. Development 2011; 138:1069-79. [PMID: 21343362 DOI: 10.1242/dev.059501] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous studies demonstrated that a subset of synMuv B mutants ectopically misexpress germline-specific P-granule proteins in their somatic cells, suggesting a failure to properly orchestrate a soma/germline fate decision. Surprisingly, this fate confusion does not affect viability at low to ambient temperatures. Here, we show that, when grown at high temperature, a majority of synMuv B mutants irreversibly arrest at the L1 stage. High temperature arrest (HTA) is accompanied by upregulation of many genes characteristic of germ line, including genes encoding components of the synaptonemal complex and other meiosis proteins. HTA is suppressed by loss of global regulators of germline chromatin, including MES-4, MRG-1, ISW-1 and the MES-2/3/6 complex, revealing that arrest is caused by somatic cells possessing a germline-like chromatin state. Germline genes are preferentially misregulated in the intestine, and necessity and sufficiency tests demonstrate that the intestine is the tissue responsible for HTA. We propose that synMuv B mutants fail to erase or antagonize an inherited germline chromatin state in somatic cells during embryonic and early larval development. As a consequence, somatic cells gain a germline program of gene expression in addition to their somatic program, leading to a mixed fate. Somatic expression of germline genes is enhanced at elevated temperature, leading to developmentally compromised somatic cells and arrest of newly hatched larvae.
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Affiliation(s)
- Lisa N Petrella
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA 95064, USA
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33
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Tabuchi TM, Deplancke B, Osato N, Zhu LJ, Barrasa MI, Harrison MM, Horvitz HR, Walhout AJM, Hagstrom KA. Chromosome-biased binding and gene regulation by the Caenorhabditis elegans DRM complex. PLoS Genet 2011; 7:e1002074. [PMID: 21589891 PMCID: PMC3093354 DOI: 10.1371/journal.pgen.1002074] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 03/25/2011] [Indexed: 01/28/2023] Open
Abstract
DRM is a conserved transcription factor complex that includes E2F/DP and pRB family proteins and plays important roles in development and cancer. Here we describe new aspects of DRM binding and function revealed through genome-wide analyses of the Caenorhabditis elegans DRM subunit LIN-54. We show that LIN-54 DNA-binding activity recruits DRM to promoters enriched for adjacent putative E2F/DP and LIN-54 binding sites, suggesting that these two DNA-binding moieties together direct DRM to its target genes. Chromatin immunoprecipitation and gene expression profiling reveals conserved roles for DRM in regulating genes involved in cell division, development, and reproduction. We find that LIN-54 promotes expression of reproduction genes in the germline, but prevents ectopic activation of germline-specific genes in embryonic soma. Strikingly, C. elegans DRM does not act uniformly throughout the genome: the DRM recruitment motif, DRM binding, and DRM-regulated embryonic genes are all under-represented on the X chromosome. However, germline genes down-regulated in lin-54 mutants are over-represented on the X chromosome. We discuss models for how loss of autosome-bound DRM may enhance germline X chromosome silencing. We propose that autosome-enriched binding of DRM arose in C. elegans as a consequence of germline X chromosome silencing and the evolutionary redistribution of germline-expressed and essential target genes to autosomes. Sex chromosome gene regulation may thus have profound evolutionary effects on genome organization and transcriptional regulatory networks.
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Affiliation(s)
- Tomoko M. Tabuchi
- Program in Molecular Medicine and Program in Cell Dynamics, University of
Massachusetts Medical School, Worcester, Massachusetts, United States of
America
| | - Bart Deplancke
- Program in Gene Function and Expression and Program in Molecular
Medicine, University of Massachusetts Medical School, Worcester, Massachusetts,
United States of America
| | - Naoki Osato
- Program in Gene Function and Expression and Program in Molecular
Medicine, University of Massachusetts Medical School, Worcester, Massachusetts,
United States of America
| | - Lihua J. Zhu
- Program in Gene Function and Expression and Program in Molecular
Medicine, University of Massachusetts Medical School, Worcester, Massachusetts,
United States of America
| | - M. Inmaculada Barrasa
- Program in Gene Function and Expression and Program in Molecular
Medicine, University of Massachusetts Medical School, Worcester, Massachusetts,
United States of America
| | - Melissa M. Harrison
- Howard Hughes Medical Institute, Department of Biology, Massachusetts
Institute of Technology, Cambridge, Massachusetts, United States of
America
| | - H. Robert Horvitz
- Howard Hughes Medical Institute, Department of Biology, Massachusetts
Institute of Technology, Cambridge, Massachusetts, United States of
America
| | - Albertha J. M. Walhout
- Program in Gene Function and Expression and Program in Molecular
Medicine, University of Massachusetts Medical School, Worcester, Massachusetts,
United States of America
| | - Kirsten A. Hagstrom
- Program in Molecular Medicine and Program in Cell Dynamics, University of
Massachusetts Medical School, Worcester, Massachusetts, United States of
America
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34
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Spencer WC, Zeller G, Watson JD, Henz SR, Watkins KL, McWhirter RD, Petersen S, Sreedharan VT, Widmer C, Jo J, Reinke V, Petrella L, Strome S, Von Stetina SE, Katz M, Shaham S, Rätsch G, Miller DM. A spatial and temporal map of C. elegans gene expression. Genome Res 2011; 21:325-41. [PMID: 21177967 PMCID: PMC3032935 DOI: 10.1101/gr.114595.110] [Citation(s) in RCA: 223] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 12/08/2010] [Indexed: 01/31/2023]
Abstract
The C. elegans genome has been completely sequenced, and the developmental anatomy of this model organism is described at single-cell resolution. Here we utilize strategies that exploit this precisely defined architecture to link gene expression to cell type. We obtained RNAs from specific cells and from each developmental stage using tissue-specific promoters to mark cells for isolation by FACS or for mRNA extraction by the mRNA-tagging method. We then generated gene expression profiles of more than 30 different cells and developmental stages using tiling arrays. Machine-learning-based analysis detected transcripts corresponding to established gene models and revealed novel transcriptionally active regions (TARs) in noncoding domains that comprise at least 10% of the total C. elegans genome. Our results show that about 75% of transcripts with detectable expression are differentially expressed among developmental stages and across cell types. Examination of known tissue- and cell-specific transcripts validates these data sets and suggests that newly identified TARs may exercise cell-specific functions. Additionally, we used self-organizing maps to define groups of coregulated transcripts and applied regulatory element analysis to identify known transcription factor- and miRNA-binding sites, as well as novel motifs that likely function to control subsets of these genes. By using cell-specific, whole-genome profiling strategies, we have detected a large number of novel transcripts and produced high-resolution gene expression maps that provide a basis for establishing the roles of individual genes in cellular differentiation.
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Affiliation(s)
- W. Clay Spencer
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Georg Zeller
- Friedrich Miescher Laboratory of the Max Planck Society, 72076 Tübingen, Germany
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Joseph D. Watson
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Stefan R. Henz
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Kathie L. Watkins
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Rebecca D. McWhirter
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Sarah Petersen
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Vipin T. Sreedharan
- Friedrich Miescher Laboratory of the Max Planck Society, 72076 Tübingen, Germany
| | - Christian Widmer
- Friedrich Miescher Laboratory of the Max Planck Society, 72076 Tübingen, Germany
| | - Jeanyoung Jo
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Valerie Reinke
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Lisa Petrella
- Department of MCD Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Susan Strome
- Department of MCD Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Stephen E. Von Stetina
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Menachem Katz
- Laboratory of Developmental Genetics, The Rockefeller University, New York, New York 10065, USA
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, New York 10065, USA
| | - Gunnar Rätsch
- Friedrich Miescher Laboratory of the Max Planck Society, 72076 Tübingen, Germany
| | - David M. Miller
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
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Waters K, Yang AZ, Reinke V. Genome-wide analysis of germ cell proliferation in C.elegans identifies VRK-1 as a key regulator of CEP-1/p53. Dev Biol 2010; 344:1011-25. [PMID: 20599896 DOI: 10.1016/j.ydbio.2010.06.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 05/28/2010] [Accepted: 06/16/2010] [Indexed: 01/22/2023]
Abstract
Proliferating germ cells in Caenorhabditiselegans provide a useful model system for deciphering fundamental mechanisms underlying the balance between proliferation and differentiation. Using gene expression profiling, we identified approximately 200 genes upregulated in the proliferating germ cells of C. elegans. Functional characterization using RNA-mediated interference demonstrated that over forty of these factors are required for normal germline proliferation and development. Detailed analysis of two of these factors defined an important regulatory relationship controlling germ cell proliferation. We established that the kinase VRK-1 is required for normal germ cell proliferation, and that it acts in part to regulate CEP-1(p53) activity. Loss of cep-1 significantly rescued the proliferation defects of vrk-1 mutants. We suggest that VRK-1 prevents CEP-1 from triggering an inappropriate cell cycle arrest, thereby promoting germ cell proliferation. This finding reveals a previously unsuspected mechanism for negative regulation of p53 activity in germ cells to control proliferation.
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36
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Dosage-sensitive function of retinoblastoma related and convergent epigenetic control are required during the Arabidopsis life cycle. PLoS Genet 2010; 6:e1000988. [PMID: 20585548 PMCID: PMC2887464 DOI: 10.1371/journal.pgen.1000988] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Accepted: 05/14/2010] [Indexed: 11/19/2022] Open
Abstract
The plant life cycle alternates between two distinct multi-cellular generations, the reduced gametophytes and the dominant sporophyte. Little is known about how generation-specific cell fate, differentiation, and development are controlled by the core regulators of the cell cycle. In Arabidopsis, RETINOBLASTOMA RELATED (RBR), an evolutionarily ancient cell cycle regulator, controls cell proliferation, differentiation, and regulation of a subset of Polycomb Repressive Complex 2 (PRC2) genes and METHYLTRANSFERASE 1 (MET1) in the male and female gametophytes, as well as cell fate establishment in the male gametophyte. Here we demonstrate that RBR is also essential for cell fate determination in the female gametophyte, as revealed by loss of cell-specific marker expression in all the gametophytic cells that lack RBR. Maintenance of genome integrity also requires RBR, because diploid plants heterozygous for rbr (rbr/RBR) produce an abnormal portion of triploid offspring, likely due to gametic genome duplication. While the sporophyte of the diploid mutant plants phenocopied wild type due to the haplosufficiency of RBR, genetic analysis of tetraploid plants triplex for rbr (rbr/rbr/rbr/RBR) revealed that RBR has a dosage-dependent pleiotropic effect on sporophytic development, trichome differentiation, and regulation of PRC2 subunit genes CURLY LEAF (CLF) and VERNALIZATION 2 (VRN2), and MET1 in leaves. There were, however, no obvious cell cycle and cell proliferation defects in these plant tissues, suggesting that a single functional RBR copy in tetraploids is capable of maintaining normal cell division but is not sufficient for distinct differentiation and developmental processes. Conversely, in leaves of mutants in sporophytic PRC2 subunits, trichome differentiation was also affected and expression of RBR and MET1 was reduced, providing evidence for a RBR-PRC2-MET1 regulatory feedback loop involved in sporophyte development. Together, dosage-sensitive RBR function and its genetic interaction with PRC2 genes and MET1 must have been recruited during plant evolution to control distinct generation-specific cell fate, differentiation, and development.
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Niwa R, Hada K, Moliyama K, Ohniwa RL, Tan YM, Olsson-Carter K, Chi W, Reinke V, Slack FJ. C. elegans sym-1 is a downstream target of the hunchback-like-1 developmental timing transcription factor. Cell Cycle 2009; 8:4147-54. [PMID: 19923914 DOI: 10.4161/cc.8.24.10292] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In the nematode Caenorhabditis elegans, the let-7 microRNA (miRNA) and its family members control the timing of key developmental events in part by directly regulating expression of hunchback-like-1 (hbl-1). C. elegans hbl-1 mutants display multiple developmental timing deficiencies, including cell cycle defects during larval development. While hbl-1 is predicted to encode a transcriptional regulator, downstream targets of HBL-1 have not been fully elucidated. Here we report using microarray analysis to uncover genes downstream of HBL-1. We established a transgenic strain that overexpresses hbl-1 under the control of a heat shock promoter. Heat shock-induced hbl-1 overexpression led to retarded hypodermal structures at the adult stage, opposite to the effect seen in loss of function (lf) hbl-1 mutants. The microarray screen identified numerous potential genes that are upregulated or downregulated by HBL-1, including sym-1, which encodes a leucine-rich repeat protein with a signal sequence. We found an increase in sym-1 transcription in the heat shock-induced hbl-1 overexpression strain, while loss of hbl-1 function caused a decrease in sym-1 expression levels. Furthermore, we found that sym-1(lf) modified the hypodermal abnormalities in hbl-1 mutants. Given that SYM-1 is a protein secreted from hypodermal cells to the surrounding cuticle, we propose that the adult-specific cuticular structures may be under the temporal control of HBL-1 through regulation of sym-1 transcription.
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Affiliation(s)
- Ryusuke Niwa
- Initiative for the Promotion of Young Scientists' Independent Research, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
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Identification and expression analysis of two zebrafish E2F5 genes during oogenesis and development. Mol Biol Rep 2009; 37:1773-80. [PMID: 19578977 DOI: 10.1007/s11033-009-9605-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Accepted: 06/25/2009] [Indexed: 01/26/2023]
Abstract
During the process of screening genes that are preferentially expressed in zebrafish germ cells, we isolated an E2F family member zE2F5b, which is a truncated isoform of zebrafish E2F5a. The E2F transcription factors are thought to play an essential role in cell cycle progression. Reverse transcription polymerase chain reaction and whole mount in situ hybridization analyses have demonstrated that both zE2F5a and zE2F5b mRNAs are predominantly expressed in stage I and II oocytes. In early development, the two zE2F5 transcripts are expressed by many parts of the embryo and are then restricted to the brain area. Interestingly, zE2F5b mRNA is detected later in the lens and optic tectum while zE2F5a mRNA is absent. Our data suggests that E2F5 may play important roles in zebrafish brain, eye and ovarian development.
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39
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Chikina MD, Huttenhower C, Murphy CT, Troyanskaya OG. Global prediction of tissue-specific gene expression and context-dependent gene networks in Caenorhabditis elegans. PLoS Comput Biol 2009; 5:e1000417. [PMID: 19543383 PMCID: PMC2692103 DOI: 10.1371/journal.pcbi.1000417] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Accepted: 05/14/2009] [Indexed: 01/09/2023] Open
Abstract
Tissue-specific gene expression plays a fundamental role in metazoan biology and is an important aspect of many complex diseases. Nevertheless, an organism-wide map of tissue-specific expression remains elusive due to difficulty in obtaining these data experimentally. Here, we leveraged existing whole-animal Caenorhabditis elegans microarray data representing diverse conditions and developmental stages to generate accurate predictions of tissue-specific gene expression and experimentally validated these predictions. These patterns of tissue-specific expression are more accurate than existing high-throughput experimental studies for nearly all tissues; they also complement existing experiments by addressing tissue-specific expression present at particular developmental stages and in small tissues. We used these predictions to address several experimentally challenging questions, including the identification of tissue-specific transcriptional motifs and the discovery of potential miRNA regulation specific to particular tissues. We also investigate the role of tissue context in gene function through tissue-specific functional interaction networks. To our knowledge, this is the first study producing high-accuracy predictions of tissue-specific expression and interactions for a metazoan organism based on whole-animal data. In animals, a crucial facet of any gene's function is the tissue or cell type in which that gene is expressed and the proteins that it interacts with in that cell. However, genome-wide identification of expression across the multitude of tissues of varying size and complexity is difficult to achieve experimentally. In this paper, we show that microararray data collected from whole animals can be analyzed to yield high-quality predictions of tissue-specific expression. These predictions are of better or comparable accuracy to tissue-specific expression determined from high-throughput experiments. Our results provide a global view of tissue-specific expression in Caenorhabditis elegans, allowing us to address the question of how expression patterns are regulated and to analyze how the functions of genes that are expressed in several tissues are influenced by the cellular context.
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Affiliation(s)
- Maria D Chikina
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
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40
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Chi W, Reinke V. DPL-1 (DP) acts in the germ line to coordinate ovulation and fertilization in C. elegans. Mech Dev 2009; 126:406-16. [PMID: 19368797 PMCID: PMC2680456 DOI: 10.1016/j.mod.2009.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 01/27/2009] [Accepted: 01/27/2009] [Indexed: 11/26/2022]
Abstract
Proper coordination of oogenesis, ovulation, and fertilization is essential for successful reproduction. In Caenorhabditis elegans, a strong loss-of-function mutation in dpl-1, which encodes a subunit of the E2F heterodimeric transcription factor EFL-1/DPL-1, causes severe defects during ovulation and fertilization. Here we demonstrate that the somatic gonad structure and sheath cell contraction rate appear normal in dpl-1 mutants, but that dilation of the spermatheca valve does not occur properly, causing oocytes to become trapped in the proximal gonad arm and enter endomitosis. This ovulation defect can be partially suppressed by increasing the activity of ITR-1, an inositol triphosphate receptor in the spermatheca that promotes dilation in response to IP(3) signaling. Tissue-specific rescue experiments demonstrate that expression of DPL-1 in germ cells but not the spermatheca can restore both ovulation and fertilization in dpl-1 mutants, indicating that the absence of DPL-1 likely disrupts a pro-ovulation signal originating in the oocyte that in turn stimulates the spermatheca. Moreover, we found that expression of a single EFL-1/DPL-1-responsive gene, rme-2, in the germ line of dpl-1 mutants significantly rescues ovulation, but not fertilization. Instead, other EFL-1/DPL-1-responsive genes function to promote successful fertilization. We propose that DPL-1 acts with EFL-1 in developing oocytes to directly regulate a transcriptional program that couples the critical events of ovulation and fertilization.
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Affiliation(s)
- Woo Chi
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510
| | - Valerie Reinke
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510
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41
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Abstract
Gene regulation often plays by different rules in the germline compared to the soma. In Caenorhabditis elegans, the spatial and temporal expression of germline genes is controlled post-transcriptionally via the 3' UTR rather than transcriptionally via the promoter.
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Affiliation(s)
- Valerie Reinke
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
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42
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Merritt C, Rasoloson D, Ko D, Seydoux G. 3' UTRs are the primary regulators of gene expression in the C. elegans germline. Curr Biol 2008; 18:1476-82. [PMID: 18818082 PMCID: PMC2585380 DOI: 10.1016/j.cub.2008.08.013] [Citation(s) in RCA: 297] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 07/25/2008] [Accepted: 08/05/2008] [Indexed: 11/16/2022]
Abstract
How genes are regulated to produce the correct assortment of proteins for every cell type is a fundamental question in biology. For many genes, regulation begins at the DNA level with the use of promoter sequences to control transcription. Regulation can also occur after transcription using sequences in the 3' untranslated region (UTR) of the mRNA to affect mRNA stability and/or translation [1]. The C. elegans gonad is an excellent tissue to study gene regulation during development: In the adult, germ cells are arranged in order of differentiation, with undifferentiated progenitors at one end of the gonad, cells in meiotic prophase in the middle, and gametes at the other end [2]. Using a transgenic assay, we have compared the contribution of promoters and 3' UTRs to gene regulation during germline development. We find that for most genes tested, 3' UTRs are sufficient for regulation. With the exception of promoters activated during spermatogenesis, promoters are permissive for expression in all germ cell types (from progenitors to oocytes and sperm). In progenitors, 3' UTRs inhibit the production of meiotic and oocyte proteins by posttranscriptional mechanisms involving PUF- and KH-domain RNA-binding proteins. Our findings indicate that many genes rely primarily on 3' UTRs, not promoters, for regulation during germline development.
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Affiliation(s)
- Christopher Merritt
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Center for Cell Dynamics, Johns Hopkins School of Medicine, 725 N. Wolfe St., PCTB 706, Baltimore, MD 21205, USA
| | - Dominique Rasoloson
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Center for Cell Dynamics, Johns Hopkins School of Medicine, 725 N. Wolfe St., PCTB 706, Baltimore, MD 21205, USA
| | - Darae Ko
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Center for Cell Dynamics, Johns Hopkins School of Medicine, 725 N. Wolfe St., PCTB 706, Baltimore, MD 21205, USA
| | - Geraldine Seydoux
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Center for Cell Dynamics, Johns Hopkins School of Medicine, 725 N. Wolfe St., PCTB 706, Baltimore, MD 21205, USA
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43
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Abstract
Proteins that are related to the retinoblastoma tumour suppressor pRB and the E2F transcription factor are conserved in many species of plants and animals. The mammalian orthologues of pRB and E2F are best known for their roles in cell proliferation, but it has become clear that they affect many biological processes. Here we describe the functions of pRB-related proteins and E2F proteins that have emerged from genetic and biochemical experiments in Caenorhabditis elegans and Drosophila melanogaster. The similarities that have been observed between worms, flies and mammals provide insight into the core activities of pRB and E2F proteins and show how a common regulatory module can control various biological functions in different organisms.
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Wang G, Reinke V. A C. elegans Piwi, PRG-1, regulates 21U-RNAs during spermatogenesis. Curr Biol 2008; 18:861-7. [PMID: 18501605 PMCID: PMC2494713 DOI: 10.1016/j.cub.2008.05.009] [Citation(s) in RCA: 212] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 05/07/2008] [Accepted: 05/07/2008] [Indexed: 11/25/2022]
Abstract
BACKGROUND Epigenetic regulation by diverse classes of small RNAs is mediated by the highly conserved Argonaute/Piwi family of proteins. Although Argonautes are broadly expressed, the Piwi subfamily primarily functions in the germ line. Piwi proteins are associated with germline-specific ribonucleoprotein (RNP) granules in Drosophila, zebrafish, and mouse. Depending on the species and on the specific family member, Piwis play important roles in spermatogenesis and/or in maintaining germ cell and stem cell totipotency. Piwis bind to a newly discovered class of small RNAs, called piRNAs. C. elegans contains a large set of Argonaute/Piwi-related proteins, including two closely related to piwi called prg-1 and prg-2. The function of prg-1 and prg-2 and whether piRNAs exist in C. elegans is unknown. RESULTS Here, we demonstrate that the Piwi-like protein PRG-1 is localized to P granules in germ cells entering spermatogenesis and is required for successful spermatogenesis. Loss of prg-1 causes a marked reduction in expression of a subset of mRNAs expressed during spermatogenesis, and prg-1 mutant sperm exhibit extensive defects in activation and fertilization. Moreover, prg-1 activity is required for the presence of the small RNAs called 21U-RNAs. CONCLUSIONS Our data suggest that PRG-1 promotes expression, processing, or stability of 21U-RNAs, which, in turn or in concert with PRG-1, promote proper expression of spermatogenesis transcripts.
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Affiliation(s)
- Guilin Wang
- Department of Genetics, School of Medicine, Yale University, New Haven, CT 06520, USA
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45
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Lin B, Reinke V. The candidate MAP kinase phosphorylation substrate DPL-1 (DP) promotes expression of the MAP kinase phosphatase LIP-1 in C. elegans germ cells. Dev Biol 2008; 316:50-61. [PMID: 18304523 PMCID: PMC2359152 DOI: 10.1016/j.ydbio.2007.12.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 12/21/2007] [Accepted: 12/31/2007] [Indexed: 10/22/2022]
Abstract
The highly-conserved, commonly used MAP kinase signaling cascade plays multiple integral roles in germline development in Caenorhabditis elegans. Using a functional proteomic approach, we found that the transcription factor DPL-1, a component of the LIN-35(Rb)/EFL-1(E2F)/DPL-1(DP) pathway, is a candidate phosphorylation substrate of MAP kinase. Moreover, dpl-1 genetically interacts with mpk-1(MAP kinase) to control chromosome morphology in pachytene of meiosis I, as does lin-35. However, EFL-1, the canonical DPL-1 heterodimeric partner, does not have a role in this process. Interestingly, we find that DPL-1 and EFL-1, but not LIN-35, promote the expression of a negative regulator of MPK-1, the MAP kinase phosphatase LIP-1. Two E2F consensus motifs are present upstream of the lip-1 open reading frame. Therefore, the Rb/E2F/DP pathway intersects with MAP kinase signaling at multiple points to regulate different aspects of C. elegans germ cell development. These two highly conserved pathways with major regulatory roles in proliferation and differentiation likely have multiple mechanisms for cross-talk during development across many species.
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Affiliation(s)
- Baiqing Lin
- Department of Genetics, School of Medicine, Yale University, New Haven, CT 06520 USA
| | - Valerie Reinke
- Department of Genetics, School of Medicine, Yale University, New Haven, CT 06520 USA
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Spike CA, Bader J, Reinke V, Strome S. DEPS-1 promotes P-granule assembly and RNA interference in C. elegans germ cells. Development 2008; 135:983-93. [PMID: 18234720 PMCID: PMC2435365 DOI: 10.1242/dev.015552] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
P granules are germ-cell-specific cytoplasmic structures containing RNA and protein, and required for proper germ cell development in C. elegans. PGL-1 and GLH-1 were previously identified as critical components of P granules. We have identified a new P-granule-associated protein, DEPS-1, the loss of which disrupts P-granule structure and function. DEPS-1 is required for the proper localization of PGL-1 to P granules, the accumulation of glh-1 mRNA and protein, and germ cell proliferation and fertility at elevated temperatures. In addition, DEPS-1 is required for RNA interference (RNAi) of germline-expressed genes, possibly because DEPS-1 promotes the accumulation of RDE-4, a dsRNA-binding protein required for RNAi. A genome wide analysis of gene expression in deps-1 mutant germ lines identified additional targets of DEPS-1 regulation, many of which are also regulated by the RNAi factor RDE-3. Our studies suggest that DEPS-1 is a key component of the P-granule assembly pathway and that its roles include promoting accumulation of some mRNAs, such as glh-1 and rde-4, and reducing accumulation of other mRNAs, perhaps by collaborating with RDE-3 to generate endogenous short interfering RNAs (endo-siRNAs).
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Affiliation(s)
- Caroline A. Spike
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Jason Bader
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Valerie Reinke
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Susan Strome
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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47
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Clayton JE, van den Heuvel SJL, Saito RM. Transcriptional control of cell-cycle quiescence during C. elegans development. Dev Biol 2008; 313:603-13. [PMID: 18082681 PMCID: PMC2386670 DOI: 10.1016/j.ydbio.2007.10.051] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 10/25/2007] [Accepted: 10/30/2007] [Indexed: 11/27/2022]
Abstract
During the development of the C. elegans reproductive system, cells that give rise to the vulva, the vulval precursor cells (VPCs), remain quiescent for two larval stages before resuming cell division in the third larval stage. We have identified several transcriptional regulators that contribute to this temporary cell-cycle arrest. Mutation of lin-1 or lin-31, two downstream targets of the Receptor Tyrosine kinase (RTK)/Ras/MAP kinase cascade that controls VPC cell fate, disrupts the temporary VPC quiescence. We found that the LIN-1/Ets and LIN-31/FoxB transcription factors promote expression of CKI-1, a member of the p27 family of cyclin-dependent kinase inhibitors (CKIs). LIN-1 and LIN-31 promote cki-1/Kip-1 transcription prior to their inhibition through RTK/Ras/MAPK activation. Another mutation identified in the screen defined the mdt-13 TRAP240 Mediator subunit. Further analysis of the multi-subunit Mediator complex revealed that a specific subset of its components act in VPC quiescence. These components substantially overlap with the CDK-8 module implicated in transcriptional repression. Taken together, strict control of cell-cycle quiescence during VPC development involves transcriptional induction of CKI-1 and transcriptional regulation through the Mediator complex. These transcriptional regulators represent potential molecular connections between development and the basic cell-cycle machinery.
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Affiliation(s)
- Joseph E Clayton
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755, USA
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48
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Kirienko NV, Fay DS. Transcriptome profiling of the C. elegans Rb ortholog reveals diverse developmental roles. Dev Biol 2007; 305:674-84. [PMID: 17368442 PMCID: PMC2680605 DOI: 10.1016/j.ydbio.2007.02.021] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Accepted: 02/14/2007] [Indexed: 11/25/2022]
Abstract
LIN-35 is the single C. elegans ortholog of the mammalian pocket protein family members, pRb, p107, and p130. To gain insight into the roles of pocket proteins during development, a microarray analysis was performed with lin-35 mutants. Stage-specific regulation patterns were revealed, indicating that LIN-35 plays diverse roles at distinct developmental stages. LIN-35 was found to repress the expression of many genes involved in cell proliferation in larvae, an activity that is carried out in conjunction with E2F. In addition, LIN-35 was found to regulate neuronal genes during embryogenesis and targets of the intestinal-specific GATA transcription factor, ELT-2, at multiple developmental stages. Additional findings suggest that LIN-35 functions in cell cycle regulation in embryos in a manner that is independent of E2F. A comparison of LIN-35-regulated genes with known fly and mammalian pocket protein targets revealed a high degree of overlap, indicating strong conservation of pocket protein functions in diverse phyla. Based on microarray results and our refinement of the C. elegans E2F consensus sequence, we were able to generate a comprehensive list of putative E2F-regulated genes in C. elegans. These results implicate a large number of genes previously unconnected to cell cycle control as having potential roles in this process.
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Affiliation(s)
- Natalia V. Kirienko
- University of Wyoming, College of Agriculture, Department of Molecular Biology, Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
| | - David S. Fay
- University of Wyoming, College of Agriculture, Department of Molecular Biology, Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
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49
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Beall EL, Lewis PW, Bell M, Rocha M, Jones DL, Botchan MR. Discovery of tMAC: a Drosophila testis-specific meiotic arrest complex paralogous to Myb-Muv B. Genes Dev 2007; 21:904-19. [PMID: 17403774 PMCID: PMC1847709 DOI: 10.1101/gad.1516607] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The Drosophila Myb-Muv B (MMB)/dREAM complex regulates gene expression and DNA replication site-specifically, but its activities in vivo have not been thoroughly explored. In ovarian amplification-stage follicle cell nuclei, the largest subunit, Mip130, is a negative regulator of replication, whereas another subunit, Myb, is a positive regulator. Here, we identified a mutation in mip40 and generated a mutation in mip120, two additional MMB subunits. Both mutants were viable, but mip120 mutants had many complex phenotypes including shortened longevity and severe eye defects. mip40 mutant females had severely reduced fertility, whereas mip120 mutant females were sterile, substantiating ovarian regulatory role(s) for MMB. Myb accumulation and binding to polytene chromosomes was dependent on the core factors of the MMB complex. In contrast to the documented mip130 mutant phenotypes, both mip40 and mip120 mutant males were sterile. We purified Mip40-containing complexes from testis nuclear extracts and identified tMAC, a new testis-specific meiotic arrest complex that contained Mip40, Caf1/p55, the Mip130 family member, Always early (Aly), and a Mip120 family member, Tombola (Tomb). Together, these data demonstrate that MMB serves diverse roles in different developmental pathways, and members of MMB can be found in alternative, noninteracting complexes in different cell types.
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Affiliation(s)
- Eileen L. Beall
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
| | - Peter W. Lewis
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
| | - Maren Bell
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
| | - Michael Rocha
- The Salk Institute for Biological Studies, Laboratory of Genetics, La Jolla, California 92037, USA
| | - D. Leanne Jones
- The Salk Institute for Biological Studies, Laboratory of Genetics, La Jolla, California 92037, USA
| | - Michael R. Botchan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
- Corresponding author.E-MAIL ; FAX (510) 643-1729
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50
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Takasaki T, Liu Z, Habara Y, Nishiwaki K, Nakayama JI, Inoue K, Sakamoto H, Strome S. MRG-1, an autosome-associated protein, silences X-linked genes and protects germline immortality in Caenorhabditis elegans. Development 2007; 134:757-67. [PMID: 17215300 PMCID: PMC2435364 DOI: 10.1242/dev.02771] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
MRG15, a mammalian protein related to the mortality factor MORF4, is required for cell proliferation and embryo survival. Our genetic analysis has revealed that the Caenorhabditis elegans ortholog MRG-1 serves similar roles. Maternal MRG-1 promotes embryo survival and is required for proliferation and immortality of the primordial germ cells (PGCs). As expected of a chromodomain protein, MRG-1 associates with chromatin. Unexpectedly, it is concentrated on the autosomes and not detectable on the X chromosomes. This association is not dependent on the autosome-enriched protein MES-4. Focusing on possible roles of MRG-1 in regulating gene expression, we determined that MRG-1 is required to maintain repression in the maternal germ line of transgenes on extrachromosomal arrays, and of several X-linked genes previously shown to depend on MES-4 for repression. MRG-1 is not required for PGCs to acquire transcriptional competence or for the turn-on of expression of several PGC-expressed genes (pgl-1, glh-1, glh-4 and nos-1). By contrast to this result in PGCs, MRG-1 is required for ectopic expression of those germline genes in somatic cells lacking the NuRD complex component MEP-1. We discuss how an autosome-enriched protein might repress genes on the X chromosome, promote PGC proliferation and survival, and influence the germ versus soma distinction.
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Affiliation(s)
- Teruaki Takasaki
- Department of Biology, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodaicho, Nadaku, Kobe 657-8501, Japan
| | - Zheng Liu
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Yasuaki Habara
- Department of Biology, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodaicho, Nadaku, Kobe 657-8501, Japan
| | - Kiyoji Nishiwaki
- RIKEN Center for Developmental Biology, Chuoku, Kobe 650-0047, Japan
| | - Jun-ichi Nakayama
- RIKEN Center for Developmental Biology, Chuoku, Kobe 650-0047, Japan
| | - Kunio Inoue
- Department of Biology, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodaicho, Nadaku, Kobe 657-8501, Japan
| | - Hiroshi Sakamoto
- Department of Biology, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodaicho, Nadaku, Kobe 657-8501, Japan
| | - Susan Strome
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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