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Ortega J, Wahba L, Seemann J, Chen SY, Fire AZ, Arur S. Pachytene piRNAs control discrete meiotic events during spermatogenesis and restrict gene expression in space and time. SCIENCE ADVANCES 2024; 10:eadp0466. [PMID: 39356768 PMCID: PMC11446278 DOI: 10.1126/sciadv.adp0466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 08/26/2024] [Indexed: 10/04/2024]
Abstract
Pachytene piRNAs, a Piwi-interacting RNA subclass in mammals, are hypothesized to regulate non-transposon sequences during spermatogenesis. Caenorhabditis elegans piRNAs, the 21URNAs, are implicated in regulating coding sequences; the messenger RNA targets and biological processes they control during spermatogenesis are largely unknown. We demonstrate that loss of 21URNAs compromises homolog pairing and makes it permissive for nonhomologous synapsis resulting in defects in crossover formation and chromosome segregation during spermatogenesis. We identify Polo-like kinase 3 (PLK-3), among others, as a 21URNA target. 21URNA activity restricts PLK-3 protein to proliferative cells, and expansion of PLK-3 in pachytene overlaps with the meiotic defects. Removal of plk-3 results in quantitative genetic suppression of the meiotic defects. One discrete 21URNA inhibits PLK-3 expression in late pachytene cells. Together, these results suggest that the 21URNAs function as pachytene piRNAs during C. elegans spermatogenesis. We identify their targets and meiotic events and highlight the remarkable intricacy of this multi-effector mechanism during spermatogenesis.
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Affiliation(s)
- Jacob Ortega
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Genetics, UT MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Lamia Wahba
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
- Laboratory of Non-canonical Modes of Inheritance, Rockefeller University, New York, NY 10065, USA
| | - Jacob Seemann
- Department of Genetics, UT MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Shin-Yu Chen
- Department of Genetics, UT MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Andrew Z. Fire
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Swathi Arur
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Genetics, UT MD Anderson Cancer Center, Houston, TX 77030, USA
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2
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Teterina AA, Willis JH, Baer CF, Phillips PC. Pervasive conservation of intron number and other genetic elements revealed by a chromosome-level genomic assembly of the hyper-polymorphic nematode Caenorhabditis brenneri. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.25.600681. [PMID: 38979286 PMCID: PMC11230420 DOI: 10.1101/2024.06.25.600681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
With within-species genetic diversity estimates that span the gambit of that seen across the entirety of animals, the Caenorhabditis genus of nematodes holds unique potential to provide insights into how population size and reproductive strategies influence gene and genome organization and evolution. Our study focuses on Caenorhabditis brenneri, currently known as one of the most genetically diverse nematodes within its genus and metazoan phyla. Here, we present a high-quality gapless genome assembly and annotation for C. brenneri, revealing a common nematode chromosome arrangement characterized by gene-dense central regions and repeat rich peripheral parts. Comparison of C. brenneri with other nematodes from the 'Elegans' group revealed conserved macrosynteny but a lack of microsynteny, characterized by frequent rearrangements and low correlation iof orthogroup sizes, indicative of high rates of gene turnover. We also assessed genome organization within corresponding syntenic blocks in selfing and outcrossing species, affirming that selfing species predominantly experience loss of both genes and intergenic DNA. Comparison of gene structures revealed strikingly small number of shared introns across species, yet consistent distributions of intron number and length, regardless of population size or reproductive mode, suggesting that their evolutionary dynamics are primarily reflective of functional constraints. Our study provides valuable insights into genome evolution and expands the nematode genome resources with the highly genetically diverse C. brenneri, facilitating research into various aspects of nematode biology and evolutionary processes.
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Affiliation(s)
- Anastasia A Teterina
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, USA
- Center of Parasitology, Severtsov Institute of Ecology and Evolution RAS, Moscow, Russia
| | - John H Willis
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, USA
| | - Charles F Baer
- Department of Biology, University of Florida, Gainesville, USA
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, USA
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Hockens C, Lorenzi H, Wang TT, Lei EP, Rosin LF. Chromosome segregation during spermatogenesis occurs through a unique center-kinetic mechanism in holocentric moth species. PLoS Genet 2024; 20:e1011329. [PMID: 38913752 PMCID: PMC11226059 DOI: 10.1371/journal.pgen.1011329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 07/05/2024] [Accepted: 06/03/2024] [Indexed: 06/26/2024] Open
Abstract
Precise regulation of chromosome dynamics in the germline is essential for reproductive success across species. Yet, the mechanisms underlying meiotic chromosomal events such as homolog pairing and chromosome segregation are not fully understood in many species. Here, we employ Oligopaint DNA FISH to investigate mechanisms of meiotic homolog pairing and chromosome segregation in the holocentric pantry moth, Plodia interpunctella, and compare our findings to new and previous studies in the silkworm moth, Bombyx mori, which diverged from P. interpunctella over 100 million years ago. We find that pairing in both Bombyx and Plodia spermatogenesis is initiated at gene-rich chromosome ends. Additionally, both species form rod shaped cruciform-like bivalents at metaphase I. However, unlike the telomere-oriented chromosome segregation mechanism observed in Bombyx, Plodia can orient bivalents in multiple different ways at metaphase I. Surprisingly, in both species we find that kinetochores consistently assemble at non-telomeric loci toward the center of chromosomes regardless of where chromosome centers are located in the bivalent. Additionally, sister kinetochores do not seem to be paired in these species. Instead, four distinct kinetochores are easily observed at metaphase I. Despite this, we find clear end-on microtubule attachments and not lateral microtubule attachments co-orienting these separated kinetochores. These findings challenge the classical view of segregation where paired, poleward-facing kinetochores are required for accurate homolog separation in meiosis I. Our studies here highlight the importance of exploring fundamental processes in non-model systems, as employing novel organisms can lead to the discovery of novel biology.
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Affiliation(s)
- Clio Hockens
- Unit on Chromosome Dynamics, Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Hernan Lorenzi
- TriLab Bioinformatics Group, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Tricia T. Wang
- Unit on Chromosome Dynamics, Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Elissa P. Lei
- Nuclear Organization and Gene Expression Section; Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Leah F. Rosin
- Unit on Chromosome Dynamics, Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
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4
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Ulaganathan G, Jiang H, Canio N, Oke A, Armstrong SS, Abrahamsson D, Varshavsky JR, Lam J, Cooper C, Robinson JF, Fung JC, Woodruff TJ, Allard P. Screening and characterization of 133 physiologically-relevant environmental chemicals for reproductive toxicity. Reprod Toxicol 2024; 126:108602. [PMID: 38723698 PMCID: PMC11155672 DOI: 10.1016/j.reprotox.2024.108602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 04/27/2024] [Accepted: 04/30/2024] [Indexed: 05/16/2024]
Abstract
Reproduction is a functional outcome that relies on complex cellular, tissue, and organ interactions that span the developmental period to adulthood. Thus, the assessment of its disruption by environmental chemicals would benefit significantly from scalable and innovative approaches to testing using functionally comparable reproductive models such as the nematode C. elegans. We adapted a previously described low-throughput in vivo chromosome segregation assay using C. elegans predictive of reproductive toxicity and leveraged available public data sources (ToxCast, ICE) to screen and characterize 133 physiologically-relevant chemicals in a high-throughput manner. The screening outcome was further validated in a second, independent in vivo assay assessing embryonic viability. In total, 13 chemicals were classified as reproductive toxicants with the two most active chemicals belonging to the large family of Quaternary Ammonium Compounds (QACs) commonly used as disinfectants but with limited available reproductive toxicity data. We compared the results from the C. elegans assay with ToxCast in vitro data compiled from 700+ cell response assays and 300+ signaling pathways-based assays. We did not observe a difference in the bioactivity or in the average potency (AC50) between the top and bottom chemicals. However, the intended target categories were significantly different between the classified chemicals with, in particular, an over-representation of steroid hormone targets for the high Z-score chemicals. Taken together, these results point to the value of in vivo models that scale to high-throughput level for reproductive toxicity assessment and to the need to prioritize the assessment of QACs impacts on reproduction.
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Affiliation(s)
- Gurugowtham Ulaganathan
- Institute for Society and Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Hui Jiang
- Institute for Society and Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Noah Canio
- Institute for Society and Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Ashwini Oke
- Center for Reproductive Sciences and Department of Obstetrics, Gynecology & Reproductive Sciences, UCSF, San Francisco, CA, USA
| | - Sujit Silas Armstrong
- Institute for Society and Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Dimitri Abrahamsson
- Department of Pediatrics at NYU Grossman School of Medicine, New York, NY, USA; University of California, San Francisco (UCSF), Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology and Reproductive Sciences, San Francisco, CA, USA
| | - Julia R Varshavsky
- Department of Health Sciences and Department of Civil and Environmental Engineering, Northeastern University, Boston, MA, USA
| | - Juleen Lam
- Department of Public Health, California State University, East Bay, Hayward, CA, USA
| | - Courtney Cooper
- University of California, San Francisco (UCSF), Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology and Reproductive Sciences, San Francisco, CA, USA
| | - Joshua F Robinson
- Center for Reproductive Sciences and Department of Obstetrics, Gynecology & Reproductive Sciences, UCSF, San Francisco, CA, USA
| | - Jennifer C Fung
- Center for Reproductive Sciences and Department of Obstetrics, Gynecology & Reproductive Sciences, UCSF, San Francisco, CA, USA
| | - Tracey J Woodruff
- Center for Reproductive Sciences and Department of Obstetrics, Gynecology & Reproductive Sciences, UCSF, San Francisco, CA, USA; University of California, San Francisco (UCSF), Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology and Reproductive Sciences, San Francisco, CA, USA
| | - Patrick Allard
- Institute for Society and Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
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5
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Meng Q, Borris RP, Kim HM. Torenia sp. Extracts Contain Multiple Potent Antitumor Compounds with Nematocidal Activity, Triggering an Activated DNA Damage Checkpoint and Defective Meiotic Progression. Pharmaceuticals (Basel) 2024; 17:611. [PMID: 38794181 PMCID: PMC11124231 DOI: 10.3390/ph17050611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 05/03/2024] [Accepted: 05/07/2024] [Indexed: 05/26/2024] Open
Abstract
Previously, we analyzed 316 herbal extracts to evaluate their potential nematocidal properties in Caenorhabditis elegans. In this study, our attention was directed towards Torenia sp., resulting in reduced survival and heightened larval arrest/lethality, alongside a noticeable decrease in DAPI-stained bivalent structures and disrupted meiotic progression, thus disrupting developmental processes. Notably, Torenia sp. extracts activated a DNA damage checkpoint response via the ATM/ATR and CHK-1 pathways, hindering germline development. LC-MS analysis revealed 13 compounds in the Torenia sp. extracts, including flavonoids, terpenoids, tanshinones, an analog of resveratrol, iridoids, carotenoids, fatty acids, and alkaloids. Of these, 10 are known for their antitumor activity, suggesting the potential of Torenia species beyond traditional gardening, extending into pharmaceutical and therapeutic applications.
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Affiliation(s)
- Qinghao Meng
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Robert P. Borris
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Hyun-Min Kim
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan 215316, China
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6
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Ulaganathan G, Jiang H, Canio N, Oke A, Armstrong SS, Abrahamsson D, Varshavsky JR, Lam J, Cooper C, Robinson JF, Fung JC, Woodruff TJ, Allard P. Screening and characterization of 133 physiologically-relevant environmental chemicals for reproductive toxicity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.22.584808. [PMID: 38585844 PMCID: PMC10996516 DOI: 10.1101/2024.03.22.584808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Reproduction is a functional outcome that relies on complex cellular, tissue, and organ interactions that span the developmental period to adulthood. Thus, the assessment of its disruption by environmental chemicals is remarkably painstaking in conventional toxicological animal models and does not scale up to the number of chemicals present in our environment and requiring testing. We adapted a previously described low-throughput in vivo chromosome segregation assay using C. elegans predictive of reproductive toxicity and leveraged available public data sources (ToxCast, ICE) to screen and characterize 133 physiologically-relevant chemicals in a high-throughput manner. The screening outcome was further validated in a second, independent in vivo assay assessing embryonic viability. In total, 13 chemicals were classified as reproductive toxicants with the two most active chemicals belonging to the large family of Quaternary Ammonium Compounds (QACs) commonly used as disinfectants but with limited available reproductive toxicity data. We compared the results from the C. elegans assay with ToxCast in vitro data compiled from 700+ cell response assays and 300+ signaling pathways-based assays. We did not observe a difference in the bioactivity or in average potency (AC50) between the top and bottom chemicals. However, the intended target categories were significantly different between the classified chemicals with, in particular, an over-representation of steroid hormone targets for the high Z-score chemicals. Taken together, these results point to the value of in vivo models that scale to high-throughput level for reproductive toxicity assessment and to the need to prioritize the assessment of QACs impacts on reproduction.
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7
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Tian Y, Liu L, Gao J, Wang R. Homologous chromosome pairing: The linchpin of accurate segregation in meiosis. J Cell Physiol 2024; 239:3-19. [PMID: 38032002 DOI: 10.1002/jcp.31166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 11/13/2023] [Accepted: 11/20/2023] [Indexed: 12/01/2023]
Abstract
Meiosis is a specialized cell division that occurs in sexually reproducing organisms, generating haploid gametes containing half the chromosome number through two rounds of cell division. Homologous chromosomes pair and prepare for their proper segregation in subsequent divisions. How homologous chromosomes recognize each other and achieve pairing is an important question. Early studies showed that in most organisms, homologous pairing relies on homologous recombination. However, pairing mechanisms differ across species. Evidence indicates that chromosomes are dynamic and move during early meiotic stages, facilitating pairing. Recent studies in various model organisms suggest conserved mechanisms and key regulators of homologous chromosome pairing. This review summarizes these findings and compare similarities and differences in homologous chromosome pairing mechanisms across species.
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Affiliation(s)
- Yuqi Tian
- Center for Cell Structure and Function, College of Life Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, Shandong Normal University, Jinan, China
| | - Libo Liu
- Center for Cell Structure and Function, College of Life Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, Shandong Normal University, Jinan, China
| | - Jinmin Gao
- Center for Cell Structure and Function, College of Life Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, Shandong Normal University, Jinan, China
| | - Ruoxi Wang
- Center for Cell Structure and Function, College of Life Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, Shandong Normal University, Jinan, China
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Meng Q, Pathak N, Ren X, Borris RP, Kim HM. Exploring the Impact of Onobrychis cornuta and Veratrum lobelianum Extracts on C. elegans: Implications for MAPK Modulation, Germline Development, and Antitumor Properties. Nutrients 2023; 16:8. [PMID: 38201838 PMCID: PMC10780469 DOI: 10.3390/nu16010008] [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: 10/13/2023] [Revised: 12/12/2023] [Accepted: 12/14/2023] [Indexed: 01/12/2024] Open
Abstract
In an era of increasing interest in the potential health benefits of medicinal foods, the need to assess their safety and potential toxicity remains a critical concern. While these natural remedies have garnered substantial attention for their therapeutic potential, a comprehensive understanding of their effects on living organisms is essential. We examined 316 herbal extracts to determine their potential nematocidal attributes in Caenorhabditis elegans. Approximately 16% of these extracts exhibited the capacity to induce diminished survival rates and larval arrest, establishing a correlation between larval arrest and overall worm viability. Certain extracts led to an unexpected increase in male nematodes, accompanied by a discernible reduction in DAPI-stained bivalent structures and perturbed meiotic advancement, thereby disrupting the conventional developmental processes. Notably, Onobrychis cornuta and Veratrum lobelianum extracts activated a DNA damage checkpoint response via the ATM/ATR and CHK-1 pathways, thus hindering germline development. Our LC-MS analysis revealed jervine in V. lobelianum and nine antitumor compounds in O. cornuta. Interestingly, linoleic acid replicated phenotypes induced by O. cornuta exposure, including an increased level of pCHK-1 foci, apoptosis, and the MAPK pathway. Mutants in the MAPK pathway mitigated the decline in worm survival, underscoring its importance in promoting worm viability. This study reveals complex interactions between herbal extracts and C. elegans processes, shedding light on potential antitumor effects and mechanisms. The findings provide insights into the complex landscape of herbal medicine's impact on a model organism, offering implications for broader applications.
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Affiliation(s)
- Qinghao Meng
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China; (Q.M.); (N.P.); (R.P.B.)
| | - Nishit Pathak
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China; (Q.M.); (N.P.); (R.P.B.)
| | - Xiaojing Ren
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China; (Q.M.); (N.P.); (R.P.B.)
| | - Robert P. Borris
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China; (Q.M.); (N.P.); (R.P.B.)
| | - Hyun-Min Kim
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan 215316, China
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Sorensen Turpin CG, Sloan D, LaForest M, Klebanow LU, Mitchell D, Severson AF, Bembenek JN. Securin Regulates the Spatiotemporal Dynamics of Separase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.12.571338. [PMID: 38168402 PMCID: PMC10760073 DOI: 10.1101/2023.12.12.571338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Separase is a key regulator of the metaphase to anaphase transition with multiple functions. Separase cleaves cohesin to allow chromosome segregation and localizes to vesicles to promote exocytosis in mid-anaphase. The anaphase promoting complex/cyclosome (APC/C) activates separase by ubiquitinating its inhibitory chaperone, securin, triggering its degradation. How this pathway controls the exocytic function of separase has not been investigated. During meiosis I, securin is degraded over several minutes, while separase rapidly relocalizes from kinetochore structures at the spindle and cortex to sites of action on chromosomes and vesicles at anaphase onset. The loss of cohesin coincides with the relocalization of separase to the chromosome midbivalent at anaphase onset. APC/C depletion prevents separase relocalization, while securin depletion causes precocious separase relocalization. Expression of non-degradable securin inhibits chromosome segregation, exocytosis, and separase localization to vesicles but not to the anaphase spindle. We conclude that APC/C mediated securin degradation controls separase localization. This spatiotemporal regulation will impact the effective local concentration of separase for more precise targeting of substrates in anaphase.
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Affiliation(s)
- Christopher G. Sorensen Turpin
- Current Address: Department of Obstetrics and Gynecology, C.S. Mott Center for Human Growth and Development, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Dillon Sloan
- Current Address: Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Marian LaForest
- Current Address: Columbia University, Herbert Irving Comprehensive Cancer Center, NYC, New York, United States of America
| | | | - Diana Mitchell
- Current Address: Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
| | - Aaron F. Severson
- Current Address: Center for Gene Regulation in Health and Disease and Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, Ohio, United States of America
| | - Joshua N. Bembenek
- Current Address: Department of Obstetrics and Gynecology, C.S. Mott Center for Human Growth and Development, Wayne State University School of Medicine, Detroit, Michigan, United States of America
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Lu L, Abbott AL. Male gonad-enriched microRNAs function to control sperm production in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.10.561762. [PMID: 37873419 PMCID: PMC10592766 DOI: 10.1101/2023.10.10.561762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Germ cell development and gamete production in animals require small RNA pathways. While studies indicate that microRNAs (miRNAs) are necessary for normal sperm production and function, the specific roles for individual miRNAs are largely unknown. Here, we use small RNA sequencing of dissected gonads and functional analysis of new loss of function alleles to identify functions for miRNAs in the control of fecundity and sperm production in Caenorhabditis elegans males and hermaphrodites. We describe a set of 29 male gonad-enriched miRNAs and identify a set of 3 individual miRNAs (mir-58.1, mir-83, and mir-235) and a miRNA cluster (mir-4807-4810.1) that are required for optimal sperm production at 20°C and 5 additional miRNAs (mir-49, mir-57, mir-261, and mir-357/358) that are required for sperm production at 25°C. We observed defects in meiotic progression in mir-58.1, mir-83, mir-235, and mir-4807-4810.1 mutants that may contribute to the reduced number of sperm. Further, analysis of multiple mutants of these miRNAs suggested complex genetic interactions between these miRNAs for sperm production. This study provides insights on the regulatory roles of miRNAs that promote optimal sperm production and fecundity in males and hermaphrodites.
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Affiliation(s)
- Lu Lu
- Department of Biological Sciences, Marquette University, Milwaukee, WI, 53201 USA
| | - Allison L. Abbott
- Department of Biological Sciences, Marquette University, Milwaukee, WI, 53201 USA
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Shabtai R, Tzur YB. Male-specific roles of lincRNA in C. elegans fertility. Front Cell Dev Biol 2023; 11:1115605. [PMID: 37035238 PMCID: PMC10076526 DOI: 10.3389/fcell.2023.1115605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Accepted: 03/08/2023] [Indexed: 04/11/2023] Open
Abstract
The testis is the mammalian tissue with the highest expression levels of long intergenic non-coding RNAs (lincRNAs). However, most in vivo models have not found significant reductions in male fertility when highly expressed lincRNA genes were removed. This suggests that certain lincRNAs may act redundantly or lack functional roles. In the genome of the nematode Caenorhabditis elegans, there is an order of magnitude fewer lincRNA genes than in mammals. This characteristic lowers the potential for redundancy, making it an ideal model to test these possibilities. We identified five highly and dynamically expressed lincRNAs in male C. elegans gonads and quantified the fertility of worm strains in which these genes were removed. In contrast to the hermaphrodites of deletion strains, which exhibited no significant reductions in broods, smaller brood sizes were observed in the progeny of males of three of the lincRNA deleted strains. This demonstrates reduced male fertility in worms with those genes removed. Interestingly, reduced brood size was statistically significant only in the last days of egg laying in two of these strains. This suggests the effect is due to early deterioration and aging of the transferred sperm. We detected a mild increase in embryonic lethality in only one of the strains, supporting the possibility that these lincRNAs do not affect fertility through critical roles in essential meiotic processes. Together our results indicate a sexually dimorphic outcome on fertility when lincRNA are removed and show that, unlike mammals, individual lincRNAs in C. elegans do play significant roles in male fertility.
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Lascarez-Lagunas LI, Martinez-Garcia M, Nadarajan S, Diaz-Pacheco BN, Berson E, Colaiácovo MP. Chromatin landscape, DSB levels, and cKU-70/80 contribute to patterning of meiotic DSB processing along chromosomes in C. elegans. PLoS Genet 2023; 19:e1010627. [PMID: 36706157 PMCID: PMC9907818 DOI: 10.1371/journal.pgen.1010627] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 02/08/2023] [Accepted: 01/20/2023] [Indexed: 01/28/2023] Open
Abstract
Programmed DNA double-strand break (DSB) formation is essential for achieving accurate chromosome segregation during meiosis. DSB repair timing and template choice are tightly regulated. However, little is known about how DSB distribution and the choice of repair pathway are regulated along the length of chromosomes, which has direct effects on the recombination landscape and chromosome remodeling at late prophase I. Here, we use the spatiotemporal resolution of meiosis in the Caenorhabditis elegans germline along with genetic approaches to study distribution of DSB processing and its regulation. High-resolution imaging of computationally straightened chromosomes immunostained for the RAD-51 recombinase marking DSB repair sites reveals that the pattern of RAD-51 foci throughout pachytene resembles crossover distribution in wild type. Specifically, RAD-51 foci occur primarily along the gene-poor distal thirds of the chromosomes in both early and late pachytene, and on both the X and the autosomes. However, this biased off-center distribution can be abrogated by the formation of excess DSBs. Reduced condensin function, but not an increase in total physical axial length, results in a homogeneous distribution of RAD-51 foci, whereas regulation of H3K9 methylation is required for the enrichment of RAD-51 at off-center positions. Finally, the DSB recognition heterodimer cKU-70/80, but not the non-homologous end-joining canonical ligase LIG-4, contributes to the enriched off-center distribution of RAD-51 foci. Taken together, our data supports a model by which regulation of the chromatin landscape, DSB levels, and DSB detection by cKU-70/80 collaborate to promote DSB processing by homologous recombination at off-center regions of the chromosomes in C. elegans.
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Affiliation(s)
- Laura I. Lascarez-Lagunas
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Marina Martinez-Garcia
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Saravanapriah Nadarajan
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Brianna N. Diaz-Pacheco
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Elizaveta Berson
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Mónica P. Colaiácovo
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
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13
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Li M, Li S, He Y, Wang Y, Zhang T, Li P, He Y. ZmSPO11-2 is critical for meiotic recombination in maize. Chromosome Res 2022; 30:415-428. [PMID: 35674907 DOI: 10.1007/s10577-022-09694-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 04/13/2022] [Accepted: 04/15/2022] [Indexed: 01/25/2023]
Abstract
Most plant species have three or more SPO11/TOPOVIA homologs and two TOPOVIB homologs, which associate to trigger meiotic double-strand break (DSB) formation and subsequent meiotic recombination. In Zea mays L. (maize), ZmSPO11-1 and ZmMTOPVIB have been reported to be indispensable for the initiation of meiotic recombination, yet the function of ZmSPO11-2 remains unclear. In this study, we characterized meiotic functions of ZmSPO11-2 during male meiosis in maize. Two independent Zmspo11-1 knock-out mutants exhibited normal vegetative growth but both male and female sterility. The formation of meiotic DSBs of DNA molecules was fully abolished in the Zmspo11-2 plants, leading to the defective homologous chromosome paring, synapsis, recombination, and segregation. However, the bipolar spindle assembly was not noticeably affected in Zmspo11-2 meiocytes. Overall, our results demonstrate that as its partner ZmSPO11-1 and ZmMTOPVIB, ZmSPO11-2 plays essential roles in DSB formation and homologous recombination in maize meiosis.
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Affiliation(s)
- Menghan Li
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing, 100094, China.,College of Plant Science, Tibet Agricultural and Animal Husbandry University, Nyingchi, 860000, China
| | - Shuyue Li
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing, 100094, China
| | - Yan He
- College of Plant Science, Tibet Agricultural and Animal Husbandry University, Nyingchi, 860000, China
| | - Yan Wang
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing, 100094, China
| | - Ting Zhang
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing, 100094, China
| | - Ping Li
- College of Plant Science, Tibet Agricultural and Animal Husbandry University, Nyingchi, 860000, China.
| | - Yan He
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing, 100094, China.
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14
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Rourke C, Jaramillo-Lambert A. TOP-2 is differentially required for the proper maintenance of the cohesin subunit REC-8 on meiotic chromosomes in Caenorhabditis elegans spermatogenesis and oogenesis. Genetics 2022; 222:iyac120. [PMID: 35951744 PMCID: PMC9526062 DOI: 10.1093/genetics/iyac120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 08/01/2022] [Indexed: 11/14/2022] Open
Abstract
During meiotic prophase I, accurate segregation of homologous chromosomes requires the establishment of chromosomes with a meiosis-specific architecture. The sister chromatid cohesin complex and the enzyme Topoisomerase II (TOP-2) are important components of meiotic chromosome architecture, but the relationship of these proteins in the context of meiotic chromosome segregation is poorly defined. Here, we analyzed the role of TOP-2 in the timely release of the sister chromatid cohesin subunit REC-8 during spermatogenesis and oogenesis of Caenorhabditis elegans. We show that there is a different requirement for TOP-2 in meiosis of spermatogenesis and oogenesis. The loss-of-function mutation top-2(it7) results in premature REC-8 removal in spermatogenesis, but not oogenesis. This correlates with a failure to maintain the HORMA-domain proteins HTP-1 and HTP-2 (HTP-1/2) on chromosome axes at diakinesis and mislocalization of the downstream components that control REC-8 release including Aurora B kinase. In oogenesis, top-2(it7) causes a delay in the localization of Aurora B to oocyte chromosomes but can be rescued through premature activation of the maturation promoting factor via knockdown of the inhibitor kinase WEE-1.3. The delay in Aurora B localization is associated with an increase in the length of diakinesis bivalents and wee-1.3 RNAi mediated rescue of Aurora B localization in top-2(it7) is associated with a decrease in diakinesis bivalent length. Our results imply that the sex-specific effects of TOP-2 on REC-8 release are due to differences in the temporal regulation of meiosis and chromosome structure in late prophase I in spermatogenesis and oogenesis.
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Affiliation(s)
- Christine Rourke
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
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15
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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: 11] [Impact Index Per Article: 5.5] [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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16
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Xia Q, Dang J, Wang P, Liang S, Wei X, Li X, Xiang S, Sun H, Wu D, Jing D, Wang S, Xia Y, He Q, Guo Q, Liang G. Low Female Gametophyte Fertility Contributes to the Low Seed Formation of the Diploid Loquat [ Eriobotrya Japonica (Thunb.) Lindl.] Line H30-6. FRONTIERS IN PLANT SCIENCE 2022; 13:882965. [PMID: 35677248 PMCID: PMC9168767 DOI: 10.3389/fpls.2022.882965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 04/19/2022] [Indexed: 06/15/2023]
Abstract
Loquat is a widely grown subtropic fruit because of its unique ripening season, nutrient content, and smooth texture of its fruits. However, loquat is not well-received because the fruits contain many large seeds. Therefore, the development of seedless or few-seed loquat varieties is the main objective of loquat breeding. Polyploidization is an effective approach for few-seed loquat breeding, but the resource is rare. The few-seed loquat line H30-6 was derived from a seedy variety. Additionally, H30-6 was systematically studied for its fruit characteristics, gamete fertility, pollen mother cell (PMC) meiosis, stigma receptivity, in situ pollen germination, fruit set, and karyotype. The results were as follows. (1) H30-6 produced only 1.54 seeds per fruit and the fruit edible rate was 70.77%. The fruit setting rate was 14.44% under open pollination, and the other qualities were equivalent to those of two other seedy varieties. (2) The in vitro pollen germination rate was only 4.04 and 77.46% of the H30-6 embryo sacs were abnormal. Stigma receptivity and self-compatibility in H30-6 were verified by in situ pollen germination and artificial pollination. Furthermore, the seed numbers in the fruits of H30-6 did not significantly differ among any of the pollination treatments (from 1.59 ±0.14 to 2 ± 0.17). (3) The chromosome configuration at meiotic diakinesis of H30-6 was 6.87I + 9.99II + 1.07III +0.69IV +0.24V (H30-6), and a total of 89.55% of H30-6 PMCs presented univalent chromosomes. Furthermore, chromosome lagging was the main abnormal phenomenon. Karyotype analysis showed that chromosomes of H30-6 had no recognizable karyotype abnormalities leading to unusual synapsis on the large scale above. (4) The abnormal embryo sacs of H30-6 could be divided into three main types: those remaining in the tetrad stage (13.38%), those remaining in the binucleate embryo sac stage (1.41%), and those without embryo sacs (52.82%). Therefore, we conclude that the loquat line H30-6 is a potential few-seed loquat resource. The diploid loquat line H30-6 was with low gametophyte fertility, which may be driven by abnormal meiotic synapses. The low female gamete fertility was the main reason for the few seeds. This diploid loquat line provides a new possibility for breeding a few-seed loquat at the diploid level.
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Affiliation(s)
- Qingqing Xia
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
| | - Jiangbo Dang
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
| | - Peng Wang
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
| | - Senlin Liang
- Economic Crops of Ziyang City, Ziyang City, China
| | - Xu Wei
- America Citrus Research and Education Center, University of Florida, Gainesville, FL, United States
| | - Xiaolin Li
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
| | - Suqiong Xiang
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
| | - Haiyan Sun
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
| | - Di Wu
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
| | - Danlong Jing
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
| | - Shumin Wang
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
| | - Yan Xia
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
| | - Qiao He
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
| | - Qigao Guo
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
| | - Guolu Liang
- Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Academy of Agricultural Sciences, Southwest University, Chongqing, China
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17
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Fielder SM, Kent T, Ling H, Gleason EJ, Kelly WG. A motor independent requirement for dynein light chain in Caenorhabditis elegans meiotic synapsis. Genetics 2022; 220:iyab203. [PMID: 34788833 PMCID: PMC8733469 DOI: 10.1093/genetics/iyab203] [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: 08/25/2021] [Accepted: 10/29/2021] [Indexed: 11/15/2022] Open
Abstract
The dynein motor complex is thought to aid in homolog pairing in many organisms by moving chromosomes within the nuclear periphery to promote and test homologous interactions. This precedes synaptonemal complex (SC) formation during homolog synapsis, which stabilizes homolog proximity during recombination. We observed that depletion of the dynein light chain (DLC-1) in Caenorhabditis elegans irreversibly prevents synapsis, causing an increase in off-chromatin formation of SC protein foci with increasing temperature. This requirement for DLC-1 is independent of its function in dynein motors, as SYP protein foci do not form with depletion of other dynein motor components. In contrast to normal SC-related structures, foci formed with DLC-1 depletion are resistant to dissolution with 1,6-hexanediol, similar to aggregates of SC proteins formed in high growth temperatures. Dynein light chains have been shown to act as hub proteins that interact with other proteins through a conserved binding motif. We identified a similar DLC-1 binding motif in the C. elegans SC protein SYP-2, and mutation of the putative motif causes meiosis defects that are exacerbated by elevated temperatures. We propose that DLC-1 acts as a pre-synapsis chaperone-like factor for SYP proteins to help regulate their self-association prior to the signals for SC assembly, a role that is revealed by its increased essentiality at elevated temperatures.
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Affiliation(s)
- Sara M Fielder
- Biology Department, Emory University, Atlanta, GA 30322, USA
- Program in Genetics and Molecular Biology, Emory University, Atlanta, GA 30322, USA
| | - Tori Kent
- Biology Department, Emory University, Atlanta, GA 30322, USA
| | - Huiping Ling
- Biology Department, Emory University, Atlanta, GA 30322, USA
| | | | - William G Kelly
- Biology Department, Emory University, Atlanta, GA 30322, USA
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18
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Zhang FG, Zhang RR, Gao JM. The organization, regulation, and biological functions of the synaptonemal complex. Asian J Androl 2021; 23:580-589. [PMID: 34528517 PMCID: PMC8577265 DOI: 10.4103/aja202153] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The synaptonemal complex (SC) is a meiosis-specific proteinaceous macromolecular structure that assembles between paired homologous chromosomes during meiosis in various eukaryotes. The SC has a highly conserved ultrastructure and plays critical roles in controlling multiple steps in meiotic recombination and crossover formation, ensuring accurate meiotic chromosome segregation. Recent studies in different organisms, facilitated by advances in super-resolution microscopy, have provided insights into the macromolecular structure of the SC, including the internal organization of the meiotic chromosome axis and SC central region, the regulatory pathways that control SC assembly and dynamics, and the biological functions exerted by the SC and its substructures. This review summarizes recent discoveries about how the SC is organized and regulated that help to explain the biological functions associated with this meiosis-specific structure.
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Affiliation(s)
- Feng-Guo Zhang
- Institute of Biomedical Sciences, College of Life Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, Shandong Normal University, Jinan 250014, China
| | - Rui-Rui Zhang
- Institute of Biomedical Sciences, College of Life Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, Shandong Normal University, Jinan 250014, China
| | - Jin-Min Gao
- Institute of Biomedical Sciences, College of Life Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, Shandong Normal University, Jinan 250014, China
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19
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Gonzalez de la Rosa PM, Thomson M, Trivedi U, Tracey A, Tandonnet S, Blaxter M. A telomere-to-telomere assembly of Oscheius tipulae and the evolution of rhabditid nematode chromosomes. G3-GENES GENOMES GENETICS 2021; 11:6026964. [PMID: 33561231 PMCID: PMC8022731 DOI: 10.1093/g3journal/jkaa020] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 11/25/2020] [Indexed: 12/20/2022]
Abstract
Eukaryotic chromosomes have phylogenetic persistence. In many taxa, each chromosome has a single functional centromere with essential roles in spindle attachment and segregation. Fusion and fission can generate chromosomes with no or multiple centromeres, leading to genome instability. Groups with holocentric chromosomes (where centromeric function is distributed along each chromosome) might be expected to show karyotypic instability. This is generally not the case, and in Caenorhabditis elegans, it has been proposed that the role of maintenance of a stable karyotype has been transferred to the meiotic pairing centers, which are found at one end of each chromosome. Here, we explore the phylogenetic stability of nematode chromosomes using a new telomere-to-telomere assembly of the rhabditine nematode Oscheius tipulae generated from nanopore long reads. The 60-Mb O. tipulae genome is resolved into six chromosomal molecules. We find the evidence of specific chromatin diminution at all telomeres. Comparing this chromosomal O. tipulae assembly with chromosomal assemblies of diverse rhabditid nematodes, we identify seven ancestral chromosomal elements (Nigon elements) and present a model for the evolution of nematode chromosomes through rearrangement and fusion of these elements. We identify frequent fusion events involving NigonX, the element associated with the rhabditid X chromosome, and thus sex chromosome-associated gene sets differ markedly between species. Despite the karyotypic stability, gene order within chromosomes defined by Nigon elements is not conserved. Our model for nematode chromosome evolution provides a platform for investigation of the tensions between local genome rearrangement and karyotypic evolution in generating extant genome architectures.
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Affiliation(s)
| | - Marian Thomson
- Edinburgh Genomics, School of Biology, University of Edinburgh, Edinburgh EH9 3JT, UK
| | - Urmi Trivedi
- Edinburgh Genomics, School of Biology, University of Edinburgh, Edinburgh EH9 3JT, UK
| | - Alan Tracey
- Tree of Life, Wellcome Sanger Institute, Cambridge CB10 1SA, UK
| | - Sophie Tandonnet
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo (USP), São Paulo, SP 05508-090, Brazil
| | - Mark Blaxter
- Tree of Life, Wellcome Sanger Institute, Cambridge CB10 1SA, UK
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20
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Achache H, Falk R, Lerner N, Beatus T, Tzur YB. Oocyte aging is controlled by mitogen-activated protein kinase signaling. Aging Cell 2021; 20:e13386. [PMID: 34061407 PMCID: PMC8208789 DOI: 10.1111/acel.13386] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 03/25/2021] [Accepted: 05/08/2021] [Indexed: 12/11/2022] Open
Abstract
Oogenesis is one of the first processes to fail during aging. In women, most oocytes cannot successfully complete meiotic divisions already during the fourth decade of life. Studies of the nematode Caenorhabditis elegans have uncovered conserved genetic pathways that control lifespan, but our knowledge regarding reproductive aging in worms and humans is limited. Specifically, little is known about germline internal signals that dictate the oogonial biological clock. Here, we report a thorough characterization of the changes in the worm germline during aging. We found that shortly after ovulation halts, germline proliferation declines, while apoptosis continues, leading to a gradual reduction in germ cell numbers. In late aging stages, we observed that meiotic progression is disturbed and crossover designation and DNA double-strand break repair decrease. In addition, we detected a decline in the quality of mature oocytes during aging, as reflected by decreasing size and elongation of interhomolog distance, a phenotype also observed in human oocytes. Many of these altered processes were previously attributed to MAPK signaling variations in young worms. In support of this, we observed changes in activation dynamics of MPK-1 during aging. We therefore tested the hypothesis that MAPK controls oocyte quality in aged worms using both genetic and pharmacological tools. We found that in mutants with high levels of activated MPK-1, oocyte quality deteriorates more rapidly than in wild-type worms, whereas reduction of MPK-1 levels enhances quality. Thus, our data suggest that MAPK signaling controls germline aging and could be used to attenuate the rate of oogenesis quality decline.
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Affiliation(s)
- Hanna Achache
- Department of GeneticsInstitute of Life SciencesThe Hebrew University of JerusalemJerusalemIsrael
| | - Roni Falk
- Department of GeneticsInstitute of Life SciencesThe Hebrew University of JerusalemJerusalemIsrael
| | - Noam Lerner
- Department of NeurobiologyThe Institute of Life ScienceThe Hebrew University of JerusalemJerusalemIsrael
- The Alexander Grass Center for BioengineeringThe Rachel and Selim Benin School of Computer Science and EngineeringThe Hebrew University of JerusalemJerusalemIsrael
| | - Tsevi Beatus
- Department of NeurobiologyThe Institute of Life ScienceThe Hebrew University of JerusalemJerusalemIsrael
- The Alexander Grass Center for BioengineeringThe Rachel and Selim Benin School of Computer Science and EngineeringThe Hebrew University of JerusalemJerusalemIsrael
| | - Yonatan B. Tzur
- Department of GeneticsInstitute of Life SciencesThe Hebrew University of JerusalemJerusalemIsrael
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21
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Rourke CK, Murat D, Hansen TJ, Jaramillo-Lambert A. Endogenous localization of TOP-2 in C. elegans using a C-terminal GFP-tag. MICROPUBLICATION BIOLOGY 2021; 2021:10.17912/micropub.biology.000402. [PMID: 34095779 PMCID: PMC8170510 DOI: 10.17912/micropub.biology.000402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To investigate the dynamic localization of Topoisomerase II in live C. elegans we have generated a C-terminally GFP-tagged version of TOP-2 at the endogenous locus. We found that TOP-2::GFP localizes in a similar pattern to the previously published TOP-2::3XFLAG strain and does not disrupt the meiotic chromosome segregation functions of this enzyme.
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Affiliation(s)
- Christine K. Rourke
- Department of Biological Sciences, University of Delaware, Newark, Delaware 19716
| | - Darline Murat
- Department of Biological Sciences, University of Delaware, Newark, Delaware 19716
| | - Tyler J. Hansen
- Currently-Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37205
| | - Aimee Jaramillo-Lambert
- Department of Biological Sciences, University of Delaware, Newark, Delaware 19716,
Correspondence to: Aimee Jaramillo-Lambert ()
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22
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Nadarajan S, Altendorfer E, Saito TT, Martinez-Garcia M, Colaiácovo MP. HIM-17 regulates the position of recombination events and GSP-1/2 localization to establish short arm identity on bivalents in meiosis. Proc Natl Acad Sci U S A 2021; 118:e2016363118. [PMID: 33883277 PMCID: PMC8092412 DOI: 10.1073/pnas.2016363118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The position of recombination events established along chromosomes in early prophase I and the chromosome remodeling that takes place in late prophase I are intrinsically linked steps of meiosis that need to be tightly regulated to ensure accurate chromosome segregation and haploid gamete formation. Here, we show that RAD-51 foci, which form at the sites of programmed meiotic DNA double-strand breaks (DSBs), exhibit a biased distribution toward off-centered positions along the chromosomes in wild-type Caenorhabditis elegans, and we identify two meiotic roles for chromatin-associated protein HIM-17 that ensure normal chromosome remodeling in late prophase I. During early prophase I, HIM-17 regulates the distribution of DSB-dependent RAD-51 foci and crossovers on chromosomes, which is critical for the formation of distinct chromosome subdomains (short and long arms of the bivalents) later during chromosome remodeling. During late prophase I, HIM-17 promotes the normal expression and localization of protein phosphatases GSP-1/2 to the surface of the bivalent chromosomes and may promote GSP-1 phosphorylation, thereby antagonizing Aurora B kinase AIR-2 loading on the long arms and preventing premature loss of sister chromatid cohesion. We propose that HIM-17 plays distinct roles at different stages during meiotic progression that converge to promote normal chromosome remodeling and accurate chromosome segregation.
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Affiliation(s)
| | - Elisabeth Altendorfer
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115
| | - Takamune T Saito
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115
| | | | - Monica P Colaiácovo
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115
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23
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Li Q, Engebrecht J. BRCA1 and BRCA2 Tumor Suppressor Function in Meiosis. Front Cell Dev Biol 2021; 9:668309. [PMID: 33996823 PMCID: PMC8121103 DOI: 10.3389/fcell.2021.668309] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 03/19/2021] [Indexed: 12/12/2022] Open
Abstract
Meiosis is a specialized cell cycle that results in the production of haploid gametes for sexual reproduction. During meiosis, homologous chromosomes are connected by chiasmata, the physical manifestation of crossovers. Crossovers are formed by the repair of intentionally induced double strand breaks by homologous recombination and facilitate chromosome alignment on the meiotic spindle and proper chromosome segregation. While it is well established that the tumor suppressors BRCA1 and BRCA2 function in DNA repair and homologous recombination in somatic cells, the functions of BRCA1 and BRCA2 in meiosis have received less attention. Recent studies in both mice and the nematode Caenorhabditis elegans have provided insight into the roles of these tumor suppressors in a number of meiotic processes, revealing both conserved and organism-specific functions. BRCA1 forms an E3 ubiquitin ligase as a heterodimer with BARD1 and appears to have regulatory roles in a number of key meiotic processes. BRCA2 is a very large protein that plays an intimate role in homologous recombination. As women with no indication of cancer but carrying BRCA mutations show decreased ovarian reserve and accumulated oocyte DNA damage, studies in these systems may provide insight into why BRCA mutations impact reproductive success in addition to their established roles in cancer.
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Affiliation(s)
- Qianyan Li
- Department of Molecular and Cellular Biology, and Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California, Davis, Davis, CA, United States
| | - JoAnne Engebrecht
- Department of Molecular and Cellular Biology, and Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California, Davis, Davis, CA, United States
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Harrell K, Day M, Smolikove S. Recruitment of MRE-11 to complex DNA damage is modulated by meiosis-specific chromosome organization. Mutat Res 2021; 822:111743. [PMID: 33975127 DOI: 10.1016/j.mrfmmm.2021.111743] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/11/2021] [Accepted: 04/15/2021] [Indexed: 12/15/2022]
Abstract
DNA double-strand breaks (DSBs) are one of the most dangerous assaults on the genome, and yet their natural and programmed production are inherent to life. When DSBs arise close together they are particularly deleterious, and their repair may require an altered form of the DNA damage response. Our understanding of how clustered DSBs are repaired in the germline is unknown. Using laser microirradiation, we examine early events in the repair of clustered DSBs in germ cells within Caenorhabditis elegans. We use precise temporal resolution to show how the recruitment of MRE-11 to complex damage is regulated, and that clustered DNA damage can recruit proteins from various repair pathways. Abrogation of non-homologous end joining or COM-1 attenuates the recruitment of MRE-11 through distinct mechanisms. The synaptonemal complex plays both positive and negative regulatory roles in these mutant contexts. These findings indicate that MRE-11 is regulated by modifying its accessibility to chromosomes.
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Affiliation(s)
- Kailey Harrell
- Department of Biology, University of Iowa, Iowa City, IA, 52241, USA
| | - Madison Day
- Department of Biology, University of Iowa, Iowa City, IA, 52241, USA
| | - Sarit Smolikove
- Department of Biology, University of Iowa, Iowa City, IA, 52241, USA.
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25
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Abstract
Meiosis is a specialized reductional cell division responsible for the formation of gametes and the generation of genetic diversity. A fundamental feature of the meiotic process is the initiation of homologous recombination (HR) by the programmed induction of DNA double-strand breaks (DSBs). Caenorhabditis elegans is a powerful experimental organism, which is used to study meiotic processes mainly due to the germline that allows for visualization of sequential stages of meiosis. C. elegans meiosis-programed DSBs are resolved through HR; hence, the germline provides a suitable model to study DSB repair. Classically direct procedures to detect and study intermediate steps in DSB repair by HR in the nematode rely on germline immunofluorescence against the strand exchange protein RAD-51.
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Hofstatter PG, Thangavel G, Castellani M, Marques A. Meiosis Progression and Recombination in Holocentric Plants: What Is Known? FRONTIERS IN PLANT SCIENCE 2021; 12:658296. [PMID: 33968114 PMCID: PMC8100227 DOI: 10.3389/fpls.2021.658296] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 03/22/2021] [Indexed: 05/02/2023]
Abstract
Differently from the common monocentric organization of eukaryotic chromosomes, the so-called holocentric chromosomes present many centromeric regions along their length. This chromosomal organization can be found in animal and plant lineages, whose distribution suggests that it has evolved independently several times. Holocentric chromosomes present an advantage: even broken chromosome parts can be correctly segregated upon cell division. However, the evolution of holocentricity brought about consequences to nuclear processes and several adaptations are necessary to cope with this new organization. Centromeres of monocentric chromosomes are involved in a two-step cohesion release during meiosis. To deal with that holocentric lineages developed different adaptations, like the chromosome remodeling strategy in Caenorhabditis elegans or the inverted meiosis in plants. Furthermore, the frequency of recombination at or around centromeres is normally very low and the presence of centromeric regions throughout the entire length of the chromosomes could potentially pose a problem for recombination in holocentric organisms. However, meiotic recombination happens, with exceptions, in those lineages in spite of their holocentric organization suggesting that the role of centromere as recombination suppressor might be altered in these lineages. Most of the available information about adaptations to meiosis in holocentric organisms is derived from the animal model C. elegans. As holocentricity evolved independently in different lineages, adaptations observed in C. elegans probably do not apply to other lineages and very limited research is available for holocentric plants. Currently, we still lack a holocentric model for plants, but good candidates may be found among Cyperaceae, a large angiosperm family. Besides holocentricity, chiasmatic and achiasmatic inverted meiosis are found in the family. Here, we introduce the main concepts of meiotic constraints and adaptations with special focus in meiosis progression and recombination in holocentric plants. Finally, we present the main challenges and perspectives for future research in the field of chromosome biology and meiosis in holocentric plants.
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Sato-Carlton A, Nakamura-Tabuchi C, Li X, Boog H, Lehmer MK, Rosenberg SC, Barroso C, Martinez-Perez E, Corbett KD, Carlton PM. Phosphoregulation of HORMA domain protein HIM-3 promotes asymmetric synaptonemal complex disassembly in meiotic prophase in Caenorhabditis elegans. PLoS Genet 2020; 16:e1008968. [PMID: 33175901 PMCID: PMC7717579 DOI: 10.1371/journal.pgen.1008968] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 12/04/2020] [Accepted: 10/17/2020] [Indexed: 11/27/2022] Open
Abstract
In the two cell divisions of meiosis, diploid genomes are reduced into complementary haploid sets through the discrete, two-step removal of chromosome cohesion, a task carried out in most eukaryotes by protecting cohesion at the centromere until the second division. In eukaryotes without defined centromeres, however, alternative strategies have been innovated. The best-understood of these is found in the nematode Caenorhabditis elegans: after the single off-center crossover divides the chromosome into two segments, or arms, several chromosome-associated proteins or post-translational modifications become specifically partitioned to either the shorter or longer arm, where they promote the correct timing of cohesion loss through as-yet unknown mechanisms. Here, we investigate the meiotic axis HORMA-domain protein HIM-3 and show that it becomes phosphorylated at its C-terminus, within the conserved “closure motif” region bound by the related HORMA-domain proteins HTP-1 and HTP-2. Binding of HTP-2 is abrogated by phosphorylation of the closure motif in in vitro assays, strongly suggesting that in vivo phosphorylation of HIM-3 likely modulates the hierarchical structure of the chromosome axis. Phosphorylation of HIM-3 only occurs on synapsed chromosomes, and similarly to other previously-described phosphorylated proteins of the synaptonemal complex, becomes restricted to the short arm after designation of crossover sites. Regulation of HIM-3 phosphorylation status is required for timely disassembly of synaptonemal complex central elements from the long arm, and is also required for proper timing of HTP-1 and HTP-2 dissociation from the short arm. Phosphorylation of HIM-3 thus plays a role in establishing the identity of short and long arms, thereby contributing to the robustness of the two-step chromosome segregation. To segregate properly in meiosis, cohesion between replicated chromosomes must remain after the first meiotic cell division, so chromosomes can be held together until they finally separate in the second division. While the majority of organisms use centromeres to protect chromosome cohesion in the first division, the nematode worm C. elegans, which lacks single centromeres, instead protects cohesion only on a segment of the chromosome known as the “long arm”. The long arm (and its complement, the short arm) are known to accumulate specific proteins and protein modifications, but it is not known how the short and long arms are first distinguished, nor how their separate functions are carried out. We report here that the chromosome axis protein HIM-3 and its modification by phosphorylation is important for ensuring the robust establishment of short and long arm functions. We show that phosphorylated HIM-3 partitions to the short arms after crossover recombination sites are designated, and HIM-3 mutants that mimic constitutive phosphorylation delay the normal establishment of the two complementary arm domains. Our findings reveal another layer of regulation to an outstanding mystery in chromosome biology.
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Affiliation(s)
| | | | - Xuan Li
- Kyoto University, Graduate School of Biostudies, Japan
| | - Hendrik Boog
- Kyoto University, Graduate School of Biostudies, Japan
| | - Madison K. Lehmer
- Department of Chemistry and Biochemistry, University of California, San Diego, United States of America
| | - Scott C. Rosenberg
- Department of Chemistry and Biochemistry, University of California, San Diego, United States of America
| | - Consuelo Barroso
- MRC London Institute of Medical Sciences, Imperial College, London
| | | | - Kevin D. Corbett
- Department of Chemistry and Biochemistry, University of California, San Diego, United States of America
- Department of Cellular and Molecular Medicine, University of California, San Diego, United States of America
- Ludwig Institute for Cancer Research, San Diego Branch, United States of America
| | - Peter Mark Carlton
- Kyoto University, Graduate School of Biostudies, Japan
- Kyoto University, Radiation Biology Center, Japan
- Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Japan
- * E-mail:
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Lascarez-Lagunas LI, Herruzo E, Grishok A, San-Segundo PA, Colaiácovo MP. DOT-1.1-dependent H3K79 methylation promotes normal meiotic progression and meiotic checkpoint function in C. elegans. PLoS Genet 2020; 16:e1009171. [PMID: 33104701 PMCID: PMC7644094 DOI: 10.1371/journal.pgen.1009171] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 11/05/2020] [Accepted: 10/06/2020] [Indexed: 01/02/2023] Open
Abstract
Epigenetic modifiers are emerging as important regulators of the genome. However, how they regulate specific processes during meiosis is not well understood. Methylation of H3K79 by the histone methyltransferase Dot1 has been shown to be involved in the maintenance of genomic stability in various organisms. In S. cerevisiae, Dot1 modulates the meiotic checkpoint response triggered by synapsis and/or recombination defects by promoting Hop1-dependent Mek1 activation and Hop1 distribution along unsynapsed meiotic chromosomes, at least in part, by regulating Pch2 localization. However, how this protein regulates meiosis in metazoans is unknown. Here, we describe the effects of H3K79me depletion via analysis of dot-1.1 or zfp-1 mutants during meiosis in Caenorhabditis elegans. We observed decreased fertility and increased embryonic lethality in dot-1.1 mutants suggesting meiotic dysfunction. We show that DOT-1.1 plays a role in the regulation of pairing, synapsis and recombination in the worm. Furthermore, we demonstrate that DOT-1.1 is an important regulator of mechanisms surveilling chromosome synapsis during meiosis. In sum, our results reveal that regulation of H3K79me plays an important role in coordinating events during meiosis in C. elegans.
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Affiliation(s)
- Laura I. Lascarez-Lagunas
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, United States of America
| | - Esther Herruzo
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas and University of Salamanca, Salamanca, Spain
| | - Alla Grishok
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, United States of America
- Genome Science Institute, Boston University School of Medicine, Boston, MA, United States of America
| | - Pedro A. San-Segundo
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas and University of Salamanca, Salamanca, Spain
| | - Mónica P. Colaiácovo
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, United States of America
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29
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Li Q, Hariri S, Engebrecht J. Meiotic Double-Strand Break Processing and Crossover Patterning Are Regulated in a Sex-Specific Manner by BRCA1-BARD1 in Caenorhabditis elegans. Genetics 2020; 216:359-379. [PMID: 32796008 PMCID: PMC7536853 DOI: 10.1534/genetics.120.303292] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 08/08/2020] [Indexed: 12/29/2022] Open
Abstract
Meiosis is regulated in a sex-specific manner to produce two distinct gametes, sperm and oocytes, for sexual reproduction. To determine how meiotic recombination is regulated in spermatogenesis, we analyzed the meiotic phenotypes of mutants in the tumor suppressor E3 ubiquitin ligase BRC-1-BRD-1 complex in Caenorhabditis elegans male meiosis. Unlike in mammals, this complex is not required for meiotic sex chromosome inactivation, the process whereby hemizygous sex chromosomes are transcriptionally silenced. Interestingly, brc-1 and brd-1 mutants show meiotic recombination phenotypes that are largely opposing to those previously reported for female meiosis. Fewer meiotic recombination intermediates marked by the recombinase RAD-51 were observed in brc-1 and brd-1 mutants, and the reduction in RAD-51 foci could be suppressed by mutation of nonhomologous-end-joining proteins. Analysis of GFP::RPA-1 revealed fewer foci in the brc-1brd-1 mutant and concentration of BRC-1-BRD-1 to sites of meiotic recombination was dependent on DNA end resection, suggesting that the complex regulates the processing of meiotic double-strand breaks to promote repair by homologous recombination. Further, BRC-1-BRD-1 is important to promote progeny viability when male meiosis is perturbed by mutations that block the pairing and synapsis of different chromosome pairs, although the complex is not required to stabilize the RAD-51 filament as in female meiosis under the same conditions. Analyses of crossover designation and formation revealed that BRC-1-BRD-1 inhibits supernumerary COs when meiosis is perturbed. Together, our findings suggest that BRC-1-BRD-1 regulates different aspects of meiotic recombination in male and female meiosis.
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Affiliation(s)
- Qianyan Li
- Department of Molecular and Cellular Biology, and Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California, Davis, California 95616
| | - Sara Hariri
- Department of Molecular and Cellular Biology, and Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California, Davis, California 95616
| | - JoAnne Engebrecht
- Department of Molecular and Cellular Biology, and Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California, Davis, California 95616
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30
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Gordon K. Recent Advances in the Genetic, Anatomical, and Environmental Regulation of the C. elegans Germ Line Progenitor Zone. J Dev Biol 2020; 8:E14. [PMID: 32707774 PMCID: PMC7559772 DOI: 10.3390/jdb8030014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 07/13/2020] [Accepted: 07/15/2020] [Indexed: 12/16/2022] Open
Abstract
The C. elegans germ line and its gonadal support cells are well studied from a developmental genetics standpoint and have revealed many foundational principles of stem cell niche biology. Among these are the observations that a niche-like cell supports a self-renewing stem cell population with multipotential, differentiating daughter cells. While genetic features that distinguish stem-like cells from their differentiating progeny have been defined, the mechanisms that structure these populations in the germ line have yet to be explained. The spatial restriction of Notch activation has emerged as an important genetic principle acting in the distal germ line. Synthesizing recent findings, I present a model in which the germ stem cell population of the C. elegans adult hermaphrodite can be recognized as two distinct anatomical and genetic populations. This review describes the recent progress that has been made in characterizing the undifferentiated germ cells and gonad anatomy, and presents open questions in the field and new directions for research to pursue.
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Affiliation(s)
- Kacy Gordon
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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31
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Garcia-Muse T, Galindo-Diaz U, Garcia-Rubio M, Martin JS, Polanowska J, O'Reilly N, Aguilera A, Boulton SJ. A Meiotic Checkpoint Alters Repair Partner Bias to Permit Inter-sister Repair of Persistent DSBs. Cell Rep 2020; 26:775-787.e5. [PMID: 30650366 PMCID: PMC6334227 DOI: 10.1016/j.celrep.2018.12.074] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 09/28/2018] [Accepted: 12/17/2018] [Indexed: 11/30/2022] Open
Abstract
Accurate meiotic chromosome segregation critically depends on the formation of inter-homolog crossovers initiated by double-strand breaks (DSBs). Inaccuracies in this process can drive aneuploidy and developmental defects, but how meiotic cells are protected from unscheduled DNA breaks remains unexplored. Here we define a checkpoint response to persistent meiotic DSBs in C. elegans that phosphorylates the synaptonemal complex (SC) to switch repair partner from the homolog to the sister chromatid. A key target of this response is the core SC component SYP-1, which is phosphorylated in response to ionizing radiation (IR) or unrepaired meiotic DSBs. Failure to phosphorylate (syp-16A) or dephosphorylate (syp-16D) SYP-1 in response to DNA damage results in chromosome non-dysjunction, hyper-sensitivity to IR-induced DSBs, and synthetic lethality with loss of brc-1BRCA1. Since BRC-1 is required for inter-sister repair, these observations reveal that checkpoint-dependent SYP-1 phosphorylation safeguards the germline against persistent meiotic DSBs by channelling repair to the sister chromatid. Meiotic DNA damage triggers phosphorylation of the synaptonemal complex (SC) ATM-ATR kinases phosphorylate the SC in response to excessive meiotic DSBs SC phosphorylation channels DNA repair to the sister chromatid
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Affiliation(s)
- Tatiana Garcia-Muse
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Av. Américo Vespucio 24, 41092 Seville, Spain; Clare Hall Laboratories, Blanche Lane, South Mimms EN6 3LD, UK.
| | - U Galindo-Diaz
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Av. Américo Vespucio 24, 41092 Seville, Spain
| | - M Garcia-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Av. Américo Vespucio 24, 41092 Seville, Spain
| | - J S Martin
- Clare Hall Laboratories, Blanche Lane, South Mimms EN6 3LD, UK
| | - J Polanowska
- Clare Hall Laboratories, Blanche Lane, South Mimms EN6 3LD, UK
| | - N O'Reilly
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, Midland Road, London, UK
| | - A Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Av. Américo Vespucio 24, 41092 Seville, Spain.
| | - Simon J Boulton
- Clare Hall Laboratories, Blanche Lane, South Mimms EN6 3LD, UK; DSB Repair Metabolism Laboratory, The Francis Crick Institute, Midland Road, London, UK.
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32
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Teterina AA, Willis JH, Phillips PC. Chromosome-Level Assembly of the Caenorhabditis remanei Genome Reveals Conserved Patterns of Nematode Genome Organization. Genetics 2020; 214:769-780. [PMID: 32111628 PMCID: PMC7153949 DOI: 10.1534/genetics.119.303018] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 02/24/2020] [Indexed: 12/23/2022] Open
Abstract
The nematode Caenorhabditis elegans is one of the key model systems in biology, including possessing the first fully assembled animal genome. Whereas C. elegans is a self-reproducing hermaphrodite with fairly limited within-population variation, its relative C. remanei is an outcrossing species with much more extensive genetic variation, making it an ideal parallel model system for evolutionary genetic investigations. Here, we greatly improve on previous assemblies by generating a chromosome-level assembly of the entire C. remanei genome (124.8 Mb of total size) using long-read sequencing and chromatin conformation capture data. Like other fully assembled genomes in the genus, we find that the C. remanei genome displays a high degree of synteny with C. elegans despite multiple within-chromosome rearrangements. Both genomes have high gene density in central regions of chromosomes relative to chromosome ends and the opposite pattern for the accumulation of repetitive elements. C. elegans and C. remanei also show similar patterns of interchromosome interactions, with the central regions of chromosomes appearing to interact with one another more than the distal ends. The new C. remanei genome presented here greatly augments the use of the Caenorhabditis as a platform for comparative genomics and serves as a basis for molecular population genetics within this highly diverse species.
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Affiliation(s)
- Anastasia A Teterina
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon 97403
- Center of Parasitology, A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow 117071, Russia
| | - John H Willis
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon 97403
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon 97403
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Hornos Carneiro MF, Shin N, Karthikraj R, Barbosa F, Kannan K, Colaiácovo MP. Antioxidant CoQ10 Restores Fertility by Rescuing Bisphenol A-Induced Oxidative DNA Damage in the Caenorhabditis elegans Germline. Genetics 2020; 214:381-395. [PMID: 31852725 PMCID: PMC7017011 DOI: 10.1534/genetics.119.302939] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 12/10/2019] [Indexed: 12/15/2022] Open
Abstract
Endocrine-disrupting chemicals are ubiquitously present in our environment, but the mechanisms by which they adversely affect human reproductive health and strategies to circumvent their effects remain largely unknown. Here, we show in Caenorhabditis elegans that supplementation with the antioxidant Coenzyme Q10 (CoQ10) rescues the reprotoxicity induced by the widely used plasticizer and endocrine disruptor bisphenol A (BPA), in part by neutralizing DNA damage resulting from oxidative stress. CoQ10 significantly reduces BPA-induced elevated levels of germ cell apoptosis, phosphorylated checkpoint kinase 1 (CHK-1), double-strand breaks (DSBs), and chromosome defects in diakinesis oocytes. BPA-induced oxidative stress, mitochondrial dysfunction, and increased gene expression of antioxidant enzymes in the germline are counteracted by CoQ10. Finally, CoQ10 treatment also reduced the levels of aneuploid embryos and BPA-induced defects observed in early embryonic divisions. We propose that CoQ10 may counteract BPA-induced reprotoxicity through the scavenging of reactive oxygen species and free radicals, and that this natural antioxidant could constitute a low-risk and low-cost strategy to attenuate the impact on fertility by BPA.
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Affiliation(s)
- Maria Fernanda Hornos Carneiro
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
- School of Pharmaceutical Sciences of Ribeirao Preto, Universidade de Sao Paulo, 14040-903, Brazil
| | - Nara Shin
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | | | - Fernando Barbosa
- School of Pharmaceutical Sciences of Ribeirao Preto, Universidade de Sao Paulo, 14040-903, Brazil
| | - Kurunthachalam Kannan
- Wadsworth Center, New York State Department of Health, Albany, New York 12201
- Department of Environmental Health Sciences, School of Public Health, University at Albany, State University of New York, New York 12201
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34
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Liu X, Zurlo G, Zhang Q. The Roles of Cullin-2 E3 Ubiquitin Ligase Complex in Cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1217:173-186. [PMID: 31898228 DOI: 10.1007/978-981-15-1025-0_11] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Posttranslational protein modifications play an important role in regulating protein stability and cellular function. There are at least eight Cullin family members. Among them, Cullin-2 forms a functional E3 ligase complex with elongin B, elongin C, RING-box protein 1 (RBX1, also called ROC1), as well as the substrate recognition subunit (SRS) to promote the substrate ubiquitination and degradation. In this book chapter, we will review Cullin-2 E3 ligase complexes that include various SRS proteins, including von Hippel Lindau (pVHL), leucine-rich repeat protein-1 (LRR-1), preferentially expressed antigen of melanoma (PRAME), sex-determining protein FEM-1 and early embryogenesis protein ZYG-11. We will focus on the VHL signaling pathway in clear cell renal cell carcinoma (ccRCC), which may reveal various therapeutic avenues in treating this lethal cancer.
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Affiliation(s)
- Xijuan Liu
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Giada Zurlo
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC, USA.,Department of Pathology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Qing Zhang
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC, USA. .,Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA. .,Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, USA. .,Department of Pathology, UT Southwestern Medical Center, Dallas, TX, USA.
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35
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Wang SY, Mao H, Shibuya H, Uzawa S, O’Brown ZK, Wesenberg S, Shin N, Saito TT, Gao J, Meyer BJ, Colaiácovo MP, Greer EL. The demethylase NMAD-1 regulates DNA replication and repair in the Caenorhabditis elegans germline. PLoS Genet 2019; 15:e1008252. [PMID: 31283754 PMCID: PMC6638966 DOI: 10.1371/journal.pgen.1008252] [Citation(s) in RCA: 16] [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: 02/05/2019] [Revised: 07/18/2019] [Accepted: 06/18/2019] [Indexed: 01/03/2023] Open
Abstract
The biological roles of nucleic acid methylation, other than at the C5-position of cytosines in CpG dinucleotides, are still not well understood. Here, we report genetic evidence for a critical role for the putative DNA demethylase NMAD-1 in regulating meiosis in C. elegans. nmad-1 mutants have reduced fertility. They show defects in prophase I of meiosis, which leads to reduced embryo production and an increased incidence of males due to defective chromosomal segregation. In nmad-1 mutant worms, nuclear staging beginning at the leptotene and zygotene stages is disorganized, the cohesin complex is mislocalized at the diplotene and diakinesis stages, and chromosomes are improperly condensed, fused, or lost by the end of diakinesis. RNA sequencing of the nmad-1 germline revealed reduced induction of DNA replication and DNA damage response genes during meiosis, which was coupled with delayed DNA replication, impaired DNA repair and increased apoptosis of maturing oocytes. To begin to understand how NMAD-1 regulates DNA replication and repair, we used immunoprecipitation and mass spectrometry to identify NMAD-1 binding proteins. NMAD-1 binds to multiple proteins that regulate DNA repair and replication, including topoisomerase TOP-2 and co-localizes with TOP-2 on chromatin. Moreover, the majority of TOP-2 binding to chromatin depends on NMAD-1. These results suggest that NMAD-1 functions at DNA replication sites to regulate DNA replication and repair during meiosis. Errors in meiosis are the leading cause of miscarriages, as well as developmental and intellectual disabilities. We have identified that NMAD-1, an enzyme which removes methyl moieties from nucleic acids, is essential for appropriate DNA damage response, DNA replication and meiosis in the nematode C. elegans. We have cytologically and genetically characterized the defects which occur due to deletion of NMAD-1 in the C. elegans germline. Additionally, we have begun to determine molecularly how NMAD-1 can regulate DNA replication, by demonstrating that NMAD-1 binds to components of the DNA replication machinery and is required for their appropriate localization to DNA. Characterizing how epigenetic modifications and the corresponding enzymes that add or remove epigenetic modifications can control the fundamental process of meiosis will have broad implications for understanding and eventually correcting errors in meiosis that disrupt normal development.
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Affiliation(s)
- Simon Yuan Wang
- Division of Newborn Medicine, Children’s Hospital Boston, Boston, Massachusetts, United States of America
- Department of Pediatrics, Harvard Medical School, Boston Massachusetts, United States of America
| | - Hui Mao
- Division of Newborn Medicine, Children’s Hospital Boston, Boston, Massachusetts, United States of America
- Department of Pediatrics, Harvard Medical School, Boston Massachusetts, United States of America
| | - Hiroki Shibuya
- Division of Newborn Medicine, Children’s Hospital Boston, Boston, Massachusetts, United States of America
- Department of Pediatrics, Harvard Medical School, Boston Massachusetts, United States of America
| | - Satoru Uzawa
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Zach Klapholz O’Brown
- Division of Newborn Medicine, Children’s Hospital Boston, Boston, Massachusetts, United States of America
- Department of Pediatrics, Harvard Medical School, Boston Massachusetts, United States of America
| | - Sage Wesenberg
- Division of Newborn Medicine, Children’s Hospital Boston, Boston, Massachusetts, United States of America
| | - Nara Shin
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Takamune T. Saito
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jinmin Gao
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Barbara J. Meyer
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Monica P. Colaiácovo
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Eric Lieberman Greer
- Division of Newborn Medicine, Children’s Hospital Boston, Boston, Massachusetts, United States of America
- Department of Pediatrics, Harvard Medical School, Boston Massachusetts, United States of America
- * E-mail:
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Charmpilas N, Tavernarakis N. Mitochondrial maturation drives germline stem cell differentiation in Caenorhabditis elegans. Cell Death Differ 2019; 27:601-617. [PMID: 31217501 PMCID: PMC7206027 DOI: 10.1038/s41418-019-0375-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 05/27/2019] [Accepted: 06/03/2019] [Indexed: 01/07/2023] Open
Abstract
The C. elegans germline recapitulates mammalian stem cell niches and provides an effective platform for investigating key aspects of stem cell biology. However, the molecular and physiological requirements for germline stem cell homeostasis remain largely elusive. Here, we report that mitochondrial biogenesis and function are crucial for germline stem cell identity. We show that general transcription activity in germline mitochondria is highly compartmentalized, and determines mitochondrial maturation. RPOM-1, the mitochondrial RNA polymerase, is differentially expressed as germ nuclei progress from the distal to the proximal gonad arm to form oocytes. Mitochondria undergo changes from globular to tubular morphology and become polarized, as they approach the proximal gonad arm. Notably, this mitochondrial maturation trajectory is evolutionarily conserved. We find that a similar transition and temporal mitochondrial RNA polymerase expression profile characterizes differentiation of mammalian stem cells. In C. elegans, ATP, and ROS production increases sharply during maturation. Impaired mitochondrial bioenergetics causes gonad syncytium tumor formation by disrupting the balance between mitosis and differentiation to oocytes, which results in a marked reduction of fecundity. Consequently, compensatory apoptosis is induced in the germline. Sperm-derived signals promote mitochondrial maturation and proper germ cell differentiation via the MEK/ERK kinase pathway. Germ cell fate decisions are determined by a crosstalk between Insulin/IGF-1 and TGF-β signaling, mitochondria and protein synthesis. Our findings demonstrate that mitochondrial transcription activity determines a shift in mitochondrial bioenergetics, which in turn regulates germline stem cell survival and differentiation. Perturbation of mitochondrial transcription hinders proper germ cell differentiation and causes germline tumor development.
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Affiliation(s)
- Nikolaos Charmpilas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece.,Department of Biology, University of Crete, Heraklion, Greece
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece. .,Department of Basic Sciences, School of Medicine, University of Crete, 70013, Heraklion, Crete, Greece.
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Tissue-Specific Split sfGFP System for Streamlined Expression of GFP Tagged Proteins in the Caenorhabditis elegans Germline. G3-GENES GENOMES GENETICS 2019; 9:1933-1943. [PMID: 30992318 PMCID: PMC6553534 DOI: 10.1534/g3.119.400162] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Identifying protein localization is a useful tool in analyzing protein function. Using GFP-fusion tags, researchers can study the function of endogenous proteins in living tissue. However, these tags are considerably large, making them difficult to insert, and they can potentially affect the normal function of these proteins. To improve on these drawbacks, we have adopted the split sfGFP system for studying the localization of proteins in the Caenorhabditis elegans germline. This system divides the “super folder” GFP into 2 fragments, allowing researchers to use CRISPR/Cas9 to tag proteins more easily with the smaller subunit, while constitutively expressing the larger subunit from another locus. These two parts are able to stably interact, producing a functional GFP when both fragments are in the same cellular compartment. Our data demonstrate that the split sfGFP system can be adapted for use in C. elegans to tag endogenous proteins with relative ease. Strains containing the tags are homozygous viable and fertile. These small subunit tags produce fluorescent signals that matched the localization patterns of the wild-type protein in the gonad. Thus, our study shows that this approach could be used for tissue-specific GFP expression from an endogenous locus.
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Achache H, Laurent L, Hecker-Mimoun Y, Ishtayeh H, Rappaport Y, Kroizer E, Colaiácovo MP, Tzur YB. Progression of Meiosis Is Coordinated by the Level and Location of MAPK Activation Via OGR-2 in Caenorhabditis elegans. Genetics 2019; 212:213-229. [PMID: 30867196 PMCID: PMC6499523 DOI: 10.1534/genetics.119.302080] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 03/07/2019] [Indexed: 02/07/2023] Open
Abstract
During meiosis, a series of evolutionarily conserved events allow for reductional chromosome division, which is required for sexual reproduction. Although individual meiotic processes have been extensively studied, we currently know far less about how meiosis is regulated and coordinated. In the Caenorhabditis elegans gonad, mitogen-activated protein kinase (MAPK) signaling drives oogenesis while undergoing spatial activation and deactivation waves. However, it is currently unclear how MAPK activation is governed and how it facilitates the progression of oogenesis. Here, we show that the oocyte and germline-related 2 (ogr-2) gene affects proper progression of oogenesis. Complete deletion of ogr-2 results in delayed meiotic entry and late spatial onset of double-strand break repair. Elevated levels of apoptosis are observed in this mutant, independent of the meiotic canonical checkpoints; however, they are dependent on the MAPK terminal member MPK-1/ERK. MPK-1 activation is elevated in diplotene in ogr-2 mutants and its aberrant spatial activation correlates with stages where meiotic progression defects are evident. Deletion of ogr-2 significantly reduces the expression of lip-1, a phosphatase reported to repress MPK-1, which is consistent with OGR-2 localization at chromatin in germ cells. We suggest that OGR-2 modulates the expression of lip-1 to promote the timely progression of meiosis through MPK-1 spatial deactivation.
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Affiliation(s)
- Hanna Achache
- Department of Genetics, Institute of Life Sciences, Hebrew University, Givat-Ram, Jerusalem 91904, Israel
| | - Lévana Laurent
- Department of Genetics, Institute of Life Sciences, Hebrew University, Givat-Ram, Jerusalem 91904, Israel
| | - Yaël Hecker-Mimoun
- Department of Genetics, Institute of Life Sciences, Hebrew University, Givat-Ram, Jerusalem 91904, Israel
| | - Hasan Ishtayeh
- Department of Genetics, Institute of Life Sciences, Hebrew University, Givat-Ram, Jerusalem 91904, Israel
| | - Yisrael Rappaport
- Department of Genetics, Institute of Life Sciences, Hebrew University, Givat-Ram, Jerusalem 91904, Israel
| | - Eitan Kroizer
- Department of Genetics, Institute of Life Sciences, Hebrew University, Givat-Ram, Jerusalem 91904, Israel
| | | | - Yonatan B Tzur
- Department of Genetics, Institute of Life Sciences, Hebrew University, Givat-Ram, Jerusalem 91904, Israel
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Link J, Jantsch V. Meiotic chromosomes in motion: a perspective from Mus musculus and Caenorhabditis elegans. Chromosoma 2019; 128:317-330. [PMID: 30877366 PMCID: PMC6823321 DOI: 10.1007/s00412-019-00698-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 01/25/2023]
Abstract
Vigorous chromosome movement during the extended prophase of the first meiotic division is conserved in most eukaryotes. The movement is crucial for the faithful segregation of homologous chromosomes into daughter cells, and thus for fertility. A prerequisite for meiotic chromosome movement is the stable and functional attachment of telomeres or chromosome ends to the nuclear envelope and their cytoplasmic coupling to the cytoskeletal forces responsible for generating movement. Important advances in understanding the components, mechanisms, and regulation of chromosome end attachment and movement have recently been made. This review focuses on insights gained from experiments into two major metazoan model organisms: the mouse, Mus musculus, and the nematode, Caenorhabditis elegans.
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Affiliation(s)
- Jana Link
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, 1030, Vienna, Austria.
| | - Verena Jantsch
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, 1030, Vienna, Austria.
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40
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Shin N, Cuenca L, Karthikraj R, Kannan K, Colaiácovo MP. Assessing effects of germline exposure to environmental toxicants by high-throughput screening in C. elegans. PLoS Genet 2019; 15:e1007975. [PMID: 30763314 PMCID: PMC6375566 DOI: 10.1371/journal.pgen.1007975] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 01/19/2019] [Indexed: 02/07/2023] Open
Abstract
Chemicals that are highly prevalent in our environment, such as phthalates and pesticides, have been linked to problems associated with reproductive health. However, rapid assessment of their impact on reproductive health and understanding how they cause such deleterious effects, remain challenging due to their fast-growing numbers and the limitations of various current toxicity assessment model systems. Here, we performed a high-throughput screen in C. elegans to identify chemicals inducing aneuploidy as a result of impaired germline function. We screened 46 chemicals that are widely present in our environment, but for which effects in the germline remain poorly understood. These included pesticides, phthalates, and chemicals used in hydraulic fracturing and crude oil processing. Of the 46 chemicals tested, 41% exhibited levels of aneuploidy higher than those detected for bisphenol A (BPA), an endocrine disruptor shown to affect meiosis, at concentrations correlating well with mammalian reproductive endpoints. We further examined three candidates eliciting aneuploidy: dibutyl phthalate (DBP), a likely endocrine disruptor and frequently used plasticizer, and the pesticides 2-(thiocyanomethylthio) benzothiazole (TCMTB) and permethrin. Exposure to these chemicals resulted in increased embryonic lethality, elevated DNA double-strand break (DSB) formation, activation of p53/CEP-1-dependent germ cell apoptosis, chromosomal abnormalities in oocytes at diakinesis, impaired chromosome segregation during early embryogenesis, and germline-specific alterations in gene expression. This study indicates that this high-throughput screening system is highly reliable for the identification of environmental chemicals inducing aneuploidy, and provides new insights into the impact of exposure to three widely used chemicals on meiosis and germline function. The ever-increasing number of new chemicals introduced into our environment poses a significant problem for risk assessment. In addition, assessing the direct impact of toxicants on human meiosis remains challenging. We successfully utilized a high-throughput platform in the nematode C. elegans, a genetically tractable model organism which shares a high degree of gene conservation with humans, to identify chemicals that affect the germline leading to aneuploidy. We assessed chemicals that are highly prevalent in the environment in worms carrying a fluorescent reporter construct allowing for the identification of X chromosome nondisjunction combined with a mutation increasing cuticle permeability for analysis of low doses of exposure. Follow up analysis of three chemicals: DBP, permethrin and TCMTB, further validated the use of this strategy. Exposure to these chemicals resulted in elevated levels of DNA double-strand breaks, activation of a DNA damage checkpoint, chromosome morphology defects in late meiotic prophase I as well as impaired early embryogenesis and germline-specific changes in gene expression. Our results support the use of this high-throughput screening system to identify environmental chemicals inducing aneuploidy, and provide new insights into the effects of exposure to DBP, permethrin, and TCMTB on meiosis and germline function.
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Affiliation(s)
- Nara Shin
- Department of Genetics, Harvard Medical School, Boston, MA, United States of America
| | - Luciann Cuenca
- Department of Genetics, Harvard Medical School, Boston, MA, United States of America
| | - Rajendiran Karthikraj
- Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, New York, United States of America
| | - Kurunthachalam Kannan
- Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, New York, United States of America
- Department of Environmental Health Sciences, School of Public Health, University at Albany, State University of New York, Albany, New York, United States of America
| | - Monica P. Colaiácovo
- Department of Genetics, Harvard Medical School, Boston, MA, United States of America
- * E-mail:
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41
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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: 5.3] [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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Hong Y, Velkova M, Silva N, Jagut M, Scheidt V, Labib K, Jantsch V, Gartner A. The conserved LEM-3/Ankle1 nuclease is involved in the combinatorial regulation of meiotic recombination repair and chromosome segregation in Caenorhabditis elegans. PLoS Genet 2018; 14:e1007453. [PMID: 29879106 PMCID: PMC6007928 DOI: 10.1371/journal.pgen.1007453] [Citation(s) in RCA: 19] [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: 09/13/2017] [Revised: 06/19/2018] [Accepted: 05/29/2018] [Indexed: 11/23/2022] Open
Abstract
Homologous recombination is essential for crossover (CO) formation and accurate chromosome segregation during meiosis. It is of considerable importance to work out how recombination intermediates are processed, leading to CO and non-crossover (NCO) outcome. Genetic analysis in budding yeast and Caenorhabditis elegans indicates that the processing of meiotic recombination intermediates involves a combination of nucleases and DNA repair enzymes. We previously reported that in C. elegans meiotic joint molecule resolution is mediated by two redundant pathways, conferred by the SLX-1 and MUS-81 nucleases, and by the HIM-6 Bloom helicase in conjunction with the XPF-1 endonuclease, respectively. Both pathways require the scaffold protein SLX-4. However, in the absence of all these enzymes, residual processing of meiotic recombination intermediates still occurs and CO formation is reduced but not abolished. Here we show that the LEM-3 nuclease, mutation of which by itself does not have an overt meiotic phenotype, genetically interacts with slx-1 and mus-81 mutants, the respective double mutants displaying 100% embryonic lethality. The combined loss of LEM-3 and MUS-81 leads to altered processing of recombination intermediates, a delayed disassembly of foci associated with CO designated sites, and the formation of univalents linked by SPO-11 dependent chromatin bridges (dissociated bivalents). However, LEM-3 foci do not colocalize with ZHP-3, a marker that congresses into CO designated sites. In addition, neither CO frequency nor distribution is altered in lem-3 single mutants or in combination with mus-81 or slx-4 mutations. Finally, we found persistent chromatin bridges during meiotic divisions in lem-3; slx-4 double mutants. Supported by the localization of LEM-3 between dividing meiotic nuclei, this data suggest that LEM-3 is able to process erroneous recombination intermediates that persist into the second meiotic division.
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Affiliation(s)
- Ye Hong
- Centre for Gene Regulation and Expression, University of Dundee, Dundee, United Kingdom
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Maria Velkova
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Vienna BioCenter, Austria
| | - Nicola Silva
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Vienna BioCenter, Austria
| | - Marlène Jagut
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Vienna BioCenter, Austria
| | - Viktor Scheidt
- Centre for Gene Regulation and Expression, University of Dundee, Dundee, United Kingdom
| | - Karim Labib
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Verena Jantsch
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Vienna BioCenter, Austria
| | - Anton Gartner
- Centre for Gene Regulation and Expression, University of Dundee, Dundee, United Kingdom
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43
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Turcotte CA, Sloat SA, Rigothi JA, Rosenkranse E, Northrup AL, Andrews NP, Checchi PM. Maintenance of Genome Integrity by Mi2 Homologs CHD-3 and LET-418 in Caenorhabditis elegans. Genetics 2018; 208:991-1007. [PMID: 29339410 PMCID: PMC5844346 DOI: 10.1534/genetics.118.300686] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 01/10/2018] [Indexed: 02/06/2023] Open
Abstract
Meiotic recombination depends upon the tightly coordinated regulation of chromosome dynamics and is essential for the production of haploid gametes. Central to this process is the formation and repair of meiotic double-stranded breaks (DSBs), which must take place within the constraints of a specialized chromatin architecture. Here, we demonstrate a role for the nucleosome remodeling and deacetylase (NuRD) complex in orchestrating meiotic chromosome dynamics in Caenorhabditis elegans Our data reveal that the conserved Mi2 homologs Chromodomain helicase DNA-binding protein (CHD-3) and its paralog LET-418 facilitate meiotic progression by ensuring faithful repair of DSBs through homologous recombination. We discovered that loss of either CHD-3 or LET-418 results in elevated p53-dependent germ line apoptosis, which relies on the activation of the conserved checkpoint kinase CHK-1 Consistent with these findings, chd-3 and let-418 mutants produce a reduced number of offspring, indicating a role for Mi2 in forming viable gametes. When Mi2 function is compromised, persisting recombination intermediates are detected in late pachytene nuclei, indicating a failure in the timely repair of DSBs. Intriguingly, our data indicate that in Mi2 mutant germ lines, a subset of DSBs are repaired by nonhomologous end joining, which manifests as chromosomal fusions. We find that meiotic defects are exacerbated in Mi2 mutants lacking CKU-80, as evidenced by increased recombination intermediates, corpses, and defects in chromosomal integrity. Taken together, our findings support a model wherein the C. elegans Mi2 complex maintains genomic integrity through reinforcement of a chromatin landscape suitable for homology-driven repair mechanisms.
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Affiliation(s)
| | - Solomon A Sloat
- Department of Biology, Marist College, Poughkeepsie, New York 12601
| | - Julia A Rigothi
- Department of Biology, Marist College, Poughkeepsie, New York 12601
| | | | | | | | - Paula M Checchi
- Department of Biology, Marist College, Poughkeepsie, New York 12601
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44
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Koury E, Harrell K, Smolikove S. Differential RPA-1 and RAD-51 recruitment in vivo throughout the C. elegans germline, as revealed by laser microirradiation. Nucleic Acids Res 2018; 46:748-764. [PMID: 29244155 PMCID: PMC5778493 DOI: 10.1093/nar/gkx1243] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 11/25/2017] [Accepted: 11/30/2017] [Indexed: 01/12/2023] Open
Abstract
Studies of the repair pathways associated with DNA double strand breaks (DSBs) are numerous, and provide evidence for cell-cycle specific regulation of homologous recombination (HR) by the regulation of its associated proteins. Laser microirradiation is a well-established method to examine in vitro kinetics of repair and allows for live-imaging of DSB repair from the moment of induction. Here we apply this method to whole, live organisms, introducing an effective system to analyze exogenous, microirradiation-induced breaks in the Caenorhabditis elegans germline. Through this method we observed the sequential kinetics of the recruitment of ssDNA binding proteins RPA-1 and RAD-51 in vivo. We analyze these kinetics throughout different regions of the germline, and thus throughout a range of developmental stages of mitotic and meiotic nuclei. Our analysis demonstrates a largely conserved timing of recruitment of ssDNA binding proteins to DSBs throughout the germline, with a delay of RAD-51 recruitment at mid-pachytene nuclei. Microirradiated nuclei are viable and undergo a slow kinetics of resolution. We observe RPA-1 and RAD-51 colocalization for hours post-microirradiation throughout the germline, suggesting that there are mixed RPA-1/RAD-51 filaments. Finally, through live imaging analysis we observed RAD-51 foci movement with low frequency of coalescence.
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Affiliation(s)
- Emily Koury
- Department of Biology, The University of Iowa, Iowa City, IA 52242, USA
| | - Kailey Harrell
- Department of Biology, The University of Iowa, Iowa City, IA 52242, USA
| | - Sarit Smolikove
- Department of Biology, The University of Iowa, Iowa City, IA 52242, USA
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45
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Bogdanov YF. Noncanonical meiosis in the nematode Caenorhabditis elegans as a model for studying the molecular bases of the homologous chromosome synapsis, crossing over, and segregation. RUSS J GENET+ 2017. [DOI: 10.1134/s102279541712002x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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46
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Sato-Carlton A, Nakamura-Tabuchi C, Chartrand SK, Uchino T, Carlton PM. Phosphorylation of the synaptonemal complex protein SYP-1 promotes meiotic chromosome segregation. J Cell Biol 2017; 217:555-570. [PMID: 29222184 PMCID: PMC5800814 DOI: 10.1083/jcb.201707161] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 10/12/2017] [Accepted: 11/08/2017] [Indexed: 12/29/2022] Open
Abstract
Chromosomes that have undergone crossing over in meiotic prophase must maintain sister chromatid cohesion somewhere along their length between the first and second meiotic divisions. Although many eukaryotes use the centromere as a site to maintain cohesion, the holocentric organism Caenorhabditis elegans instead creates two chromosome domains of unequal length termed the short arm and long arm, which become the first and second site of cohesion loss at meiosis I and II. The mechanisms that confer distinct functions to the short and long arm domains remain poorly understood. Here, we show that phosphorylation of the synaptonemal complex protein SYP-1 is required to create these domains. Once crossover sites are designated, phosphorylated SYP-1 and PLK-2 become cooperatively confined to short arms and guide phosphorylated histone H3 and the chromosomal passenger complex to the site of meiosis I cohesion loss. Our results show that PLK-2 and phosphorylated SYP-1 ensure creation of the short arm subdomain, promoting disjunction of chromosomes in meiosis I.
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Affiliation(s)
| | | | | | - Tomoki Uchino
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
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47
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Quantitative FLIM-FRET Microscopy to Monitor Nanoscale Chromatin Compaction In Vivo Reveals Structural Roles of Condensin Complexes. Cell Rep 2017; 18:1791-1803. [PMID: 28199849 DOI: 10.1016/j.celrep.2017.01.043] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 12/21/2016] [Accepted: 01/19/2017] [Indexed: 01/03/2023] Open
Abstract
How metazoan genomes are structured at the nanoscale in living cells and tissues remains unknown. Here, we adapted a quantitative FRET (Förster resonance energy transfer)-based fluorescence lifetime imaging microscopy (FLIM) approach to assay nanoscale chromatin compaction in living organisms. Caenorhabditis elegans was chosen as a model system. By measuring FRET between histone-tagged fluorescent proteins, we visualized distinct chromosomal regions and quantified the different levels of nanoscale compaction in meiotic cells. Using RNAi and repetitive extrachromosomal array approaches, we defined the heterochromatin state and showed that its architecture presents a nanoscale-compacted organization controlled by Heterochromatin Protein-1 (HP1) and SETDB1 H3-lysine-9 methyltransferase homologs in vivo. Next, we functionally explored condensin complexes. We found that condensin I and condensin II are essential for heterochromatin compaction and that condensin I additionally controls lowly compacted regions. Our data show that, in living animals, nanoscale chromatin compaction is controlled not only by histone modifiers and readers but also by condensin complexes.
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48
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Dawson JA, Methven-Kelley C, Davis GM. atz-1 Influences meiosis to maintain germline chromosomal stability in Caenorhabditis elegans. Cell Biol Int 2017; 41:1160-1168. [PMID: 28696027 DOI: 10.1002/cbin.10821] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 07/07/2017] [Indexed: 11/07/2022]
Abstract
Exchange of genetic information during meiosis occurs in all sexually reproducing species to produce haploid gametes from diploid cells. This process involves tight coordination of a meiotic specific cohesin complex, the synaptonemal complex, and DNA damage repair mechanisms. In this study, we describe a putative myosin heavy chain protein orthologous to human myosin 1, F28D1.2, which we named Abnormal Transition Zone (atz-1). Deletion of atz-1 results in embryonic lethality and a depleted transition zone, accompanied by reduced expression of the meiotic cohesin protein, REC-8. atz-1 mutants display disorganized and aggregated chromosomal bodies in diakinetic oocytes. In addition to this, atz-1 mutants are hypersensitive to mild inhibition of DNA damage repair, suggesting that DNA replication in atz-1 mutants is impaired. Moreover, the atz-1 mutant phenotype is germline specific and resupplying somatically expressed atz-1 does not rescue the reproductive defects associated with atz-1 mutants. Overall, our data suggest that atz-1 contributes to meiosis and maintains germline chromosomal stability.
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Affiliation(s)
- Joseph A Dawson
- School of Applied and Biomedical Sciences, Federation University, Churchill, Australia
| | | | - Gregory M Davis
- School of Applied and Biomedical Sciences, Federation University, Churchill, Australia
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Hiraki H, Kagoshima H, Kraus C, Schiffer PH, Ueta Y, Kroiher M, Schierenberg E, Kohara Y. Genome analysis of Diploscapter coronatus: insights into molecular peculiarities of a nematode with parthenogenetic reproduction. BMC Genomics 2017; 18:478. [PMID: 28646875 PMCID: PMC5483258 DOI: 10.1186/s12864-017-3860-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 06/13/2017] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Sexual reproduction involving the fusion of egg and sperm is prevailing among eukaryotes. In contrast, the nematode Diploscapter coronatus, a close relative of the model Caenorhabditis elegans, reproduces parthenogenetically. Neither males nor sperm have been observed and some steps of meiosis are apparently skipped in this species. To uncover the genomic changes associated with the evolution of parthenogenesis in this nematode, we carried out a genome analysis. RESULTS We obtained a 170 Mbp draft genome in only 511 scaffolds with a N50 length of 1 Mbp. Nearly 90% of these scaffolds constitute homologous pairs with a 5.7% heterozygosity on average and inversions and translocations, meaning that the 170 Mbp sequences correspond to the diploid genome. Fluorescent staining shows that the D. coronatus genome consists of two chromosomes (2n = 2). In our genome annotation, we found orthologs of 59% of the C. elegans genes. However, a number of genes were missing or very divergent. These include genes involved in sex determination (e.g. xol-1, tra-2) and meiosis (e.g. the kleisins rec-8 and coh-3/4) giving a possible explanation for the absence of males and the second meiotic division. The high degree of heterozygosity allowed us to analyze the expression level of individual alleles. Most of the homologous pairs show very similar expression levels but others exhibit a 2-5-fold difference. CONCLUSIONS Our high-quality draft genome of D. coronatus reveals the peculiarities of the genome of parthenogenesis and provides some clues to the genetic basis for parthenogenetic reproduction. This draft genome should be the basis to elucidate fundamental questions related to parthenogenesis such as its origin and mechanisms through comparative analyses with other nematodes. Furthermore, being the closest outgroup to the genus Caenorhabditis, the draft genome will help to disclose many idiosyncrasies of the model C. elegans and its congeners in future studies.
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Affiliation(s)
- Hideaki Hiraki
- Genome Biology Laboratory, National Institute of Genetics, Mishima, Japan
| | - Hiroshi Kagoshima
- Genome Biology Laboratory, National Institute of Genetics, Mishima, Japan
- Transdisciplinary Research Integration Center, Research Organization of Information and Systems, Tokyo, Japan
| | | | | | - Yumiko Ueta
- Genome Biology Laboratory, National Institute of Genetics, Mishima, Japan
| | - Michael Kroiher
- Zoologisches Institut, Universität zu Köln, Cologne, NRW Germany
| | | | - Yuji Kohara
- Genome Biology Laboratory, National Institute of Genetics, Mishima, Japan
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McClendon TB, Mainpal R, Amrit FRG, Krause MW, Ghazi A, Yanowitz JL. X Chromosome Crossover Formation and Genome Stability in Caenorhabditis elegans Are Independently Regulated by xnd-1. G3 (BETHESDA, MD.) 2016; 6:3913-3925. [PMID: 27678523 PMCID: PMC5144962 DOI: 10.1534/g3.116.035725] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 09/21/2016] [Indexed: 01/19/2023]
Abstract
The germ line efficiently combats numerous genotoxic insults to ensure the high fidelity propagation of unaltered genomic information across generations. Yet, germ cells in most metazoans also intentionally create double-strand breaks (DSBs) to promote DNA exchange between parental chromosomes, a process known as crossing over. Homologous recombination is employed in the repair of both genotoxic lesions and programmed DSBs, and many of the core DNA repair proteins function in both processes. In addition, DNA repair efficiency and crossover (CO) distribution are both influenced by local and global differences in chromatin structure, yet the interplay between chromatin structure, genome integrity, and meiotic fidelity is still poorly understood. We have used the xnd-1 mutant of Caenorhabditis elegans to explore the relationship between genome integrity and crossover formation. Known for its role in ensuring X chromosome CO formation and germ line development, we show that xnd-1 also regulates genome stability. xnd-1 mutants exhibited a mortal germ line, high embryonic lethality, high incidence of males, and sensitivity to ionizing radiation. We discovered that a hypomorphic allele of mys-1 suppressed these genome instability phenotypes of xnd-1, but did not suppress the CO defects, suggesting it serves as a separation-of-function allele. mys-1 encodes a histone acetyltransferase, whose homolog Tip60 acetylates H2AK5, a histone mark associated with transcriptional activation that is increased in xnd-1 mutant germ lines, raising the possibility that thresholds of H2AK5ac may differentially influence distinct germ line repair events. We also show that xnd-1 regulated him-5 transcriptionally, independently of mys-1, and that ectopic expression of him-5 suppressed the CO defects of xnd-1 Our work provides xnd-1 as a model in which to study the link between chromatin factors, gene expression, and genome stability.
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Affiliation(s)
- T Brooke McClendon
- Molecular Genetics and Developmental Biology Graduate Program, University of Pittsburgh School of Medicine, Pennsylvania
- Magee-Womens Research Institute, Department of Obstetrics, Gynecology, and Reproductive Services University of Pittsburgh School of Medicine, Pennsylvania 15213
| | - Rana Mainpal
- Magee-Womens Research Institute, Department of Obstetrics, Gynecology, and Reproductive Services University of Pittsburgh School of Medicine, Pennsylvania 15213
| | - Francis R G Amrit
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pennsylvania 15224
| | - Michael W Krause
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892
| | - Arjumand Ghazi
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pennsylvania 15224
| | - Judith L Yanowitz
- Molecular Genetics and Developmental Biology Graduate Program, University of Pittsburgh School of Medicine, Pennsylvania
- Magee-Womens Research Institute, Department of Obstetrics, Gynecology, and Reproductive Services University of Pittsburgh School of Medicine, Pennsylvania 15213
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