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Olaya I, Burgess SM, Rog O. Formation and resolution of meiotic chromosome entanglements and interlocks. J Cell Sci 2024; 137:jcs262004. [PMID: 38985540 PMCID: PMC11267460 DOI: 10.1242/jcs.262004] [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] [Indexed: 07/12/2024] Open
Abstract
Interactions between parental chromosomes during the formation of gametes can lead to entanglements, entrapments and interlocks between unrelated chromosomes. If unresolved, these topological constraints can lead to misregulation of exchanges between chromosomes and to chromosome mis-segregation. Interestingly, these configurations are largely resolved by the time parental chromosomes are aligned during pachytene. In this Review, we highlight the inevitability of topologically complex configurations and discuss possible mechanisms to resolve them. We focus on the dynamic nature of a conserved chromosomal interface - the synaptonemal complex - and the chromosome movements that accompany meiosis as potential mechanisms to resolve topological constraints. We highlight the advantages of the nematode Caenorhabditis elegans for understanding biophysical features of the chromosome axis and synaptonemal complex that could contribute to mechanisms underlying interlock resolution. In addition, we highlight advantages of using the zebrafish, Danio rerio, as a model to understand how entanglements and interlocks are avoided and resolved.
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Affiliation(s)
- Iván Olaya
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA
- Integrative Genetics and Genomics Graduate Group, University of California Davis, Davis, CA 95616, USA
| | - Sean M. Burgess
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA
| | - Ofer Rog
- School of Biological Sciences and Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT 84112, USA
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2
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Dubois E, Boisnard S, Bourbon HM, Yefsah K, Budin K, Debuchy R, Zhang L, Kleckner N, Zickler D, Espagne E. Canonical and noncanonical roles of Hop1 are crucial for meiotic prophase in the fungus Sordaria macrospora. PLoS Biol 2024; 22:e3002705. [PMID: 38950075 PMCID: PMC11244814 DOI: 10.1371/journal.pbio.3002705] [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: 11/03/2023] [Revised: 07/12/2024] [Accepted: 06/07/2024] [Indexed: 07/03/2024] Open
Abstract
We show here that in the fungus Sordaria macrospora, the meiosis-specific HORMA-domain protein Hop1 is not essential for the basic early events of chromosome axis development, recombination initiation, or recombination-mediated homolog coalignment/pairing. In striking contrast, Hop1 plays a critical role at the leptotene/zygotene transition which is defined by transition from pairing to synaptonemal complex (SC) formation. During this transition, Hop1 is required for maintenance of normal axis structure, formation of SC from telomere to telomere, and development of recombination foci. These hop1Δ mutant defects are DSB dependent and require Sme4/Zip1-mediated progression of the interhomolog interaction program, potentially via a pre-SC role. The same phenotype occurs not only in hop1Δ but also in absence of the cohesin Rec8 and in spo76-1, a non-null mutant of cohesin-associated Spo76/Pds5. Thus, Hop1 and cohesins collaborate at this crucial step of meiotic prophase. In addition, analysis of 4 non-null mutants that lack this transition defect reveals that Hop1 also plays important roles in modulation of axis length, homolog-axis juxtaposition, interlock resolution, and spreading of the crossover interference signal. Finally, unexpected variations in crossover density point to the existence of effects that both enhance and limit crossover formation. Links to previously described roles of the protein in other organisms are discussed.
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Affiliation(s)
- Emeline Dubois
- Université Paris-Saclay, Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Stéphanie Boisnard
- Université Paris-Saclay, Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Henri-Marc Bourbon
- Centre de Biologie Intégrative, Molecular, Cellular & Developmental Biology Unit, Université Fédérale de Toulouse, Toulouse, France
| | - Kenza Yefsah
- Université Paris-Saclay, Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Karine Budin
- Université Paris-Saclay, Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Robert Debuchy
- Université Paris-Saclay, Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Liangran Zhang
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Nancy Kleckner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Denise Zickler
- Université Paris-Saclay, Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Eric Espagne
- Université Paris-Saclay, Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
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3
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Chen L, Weir JR. The molecular machinery of meiotic recombination. Biochem Soc Trans 2024; 52:379-393. [PMID: 38348856 PMCID: PMC10903461 DOI: 10.1042/bst20230712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 02/29/2024]
Abstract
Meiotic recombination, a cornerstone of eukaryotic diversity and individual genetic identity, is essential for the creation of physical linkages between homologous chromosomes, facilitating their faithful segregation during meiosis I. This process requires that germ cells generate controlled DNA lesions within their own genome that are subsequently repaired in a specialised manner. Repair of these DNA breaks involves the modulation of existing homologous recombination repair pathways to generate crossovers between homologous chromosomes. Decades of genetic and cytological studies have identified a multitude of factors that are involved in meiotic recombination. Recent work has started to provide additional mechanistic insights into how these factors interact with one another, with DNA, and provide the molecular outcomes required for a successful meiosis. Here, we provide a review of the recent developments with a focus on protein structures and protein-protein interactions.
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Affiliation(s)
- Linda Chen
- Structural Biochemistry of Meiosis Group, Friedrich Miescher Laboratory, Max-Planck-Ring 9, 72076 Tübingen, Germany
| | - John R Weir
- Structural Biochemistry of Meiosis Group, Friedrich Miescher Laboratory, Max-Planck-Ring 9, 72076 Tübingen, Germany
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4
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Blundon JM, Cesar BI, Bae JW, Čavka I, Haversat J, Ries J, Köhler S, Kim Y. Skp1 proteins are structural components of the synaptonemal complex in C. elegans. SCIENCE ADVANCES 2024; 10:eadl4876. [PMID: 38354250 PMCID: PMC10866564 DOI: 10.1126/sciadv.adl4876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 01/12/2024] [Indexed: 02/16/2024]
Abstract
The synaptonemal complex (SC) is a zipper-like protein assembly that links homologous chromosomes to regulate recombination and segregation during meiosis. The SC has been notoriously refractory to in vitro reconstitution, thus leaving its molecular organization largely unknown. Here, we report a moonlighting function of two paralogous S-phase kinase-associated protein 1 (Skp1)-related proteins (SKR-1 and SKR-2), well-known adaptors of the Skp1-Cul1-F-box (SCF) ubiquitin ligase, as the key missing components of the SC in Caenorhabditis elegans. SKR proteins repurpose their SCF-forming interfaces to dimerize and interact with meiosis-specific SC proteins, thereby driving synapsis independent of SCF activity. SKR-1 enables the formation of the long-sought-after soluble complex with previously identified SC proteins in vitro, which we propose it to represent a complete SC building block. Our findings demonstrate how a conserved cell cycle regulator has been co-opted to interact with rapidly evolving meiotic proteins to construct the SC and provide a foundation for understanding its structure and assembly mechanisms.
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Affiliation(s)
- Joshua M. Blundon
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Brenda I. Cesar
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Jung Woo Bae
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Ivana Čavka
- The European Molecular Biology Laboratory, Heidelberg, Germany
- Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Jocelyn Haversat
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Jonas Ries
- The European Molecular Biology Laboratory, Heidelberg, Germany
| | - Simone Köhler
- The European Molecular Biology Laboratory, Heidelberg, Germany
| | - Yumi Kim
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
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5
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Hutin S, Tully MD, Brennich M. Small-Angle X-Ray Scattering for Macromolecular Complexes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 3234:163-172. [PMID: 38507206 DOI: 10.1007/978-3-031-52193-5_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Small angle X-ray scattering (SAXS) is a versatile technique that can provide unique insights in the solution structure of macromolecules and their complexes, covering the size range from small peptides to complete viral assemblies. Technological and conceptual advances in the last two decades have tremendously improved the accessibility of the technique and transformed it into an indispensable tool for structural biology. In this chapter we introduce and discuss several approaches to collecting SAXS data on macromolecular complexes, including several approaches to online chromatography. We include practical advice on experimental design and point out common pitfalls of the technique.
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Affiliation(s)
- Stephanie Hutin
- Structural Biology Group, European Synchrotron Radiation Facility, Grenoble, Grenoble, France
| | - Mark D Tully
- Structural Biology Group, European Synchrotron Radiation Facility, Grenoble, Grenoble, France
| | - Martha Brennich
- European Molecular Biology Laboratory, Grenoble, Grenoble, France.
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6
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Piñeiro López C, Rodrigues Neves AR, Čavka I, Gros OJ, Köhler S. Segmentation of C. elegans germline nuclei. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.001062. [PMID: 38148986 PMCID: PMC10750166 DOI: 10.17912/micropub.biology.001062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/05/2023] [Accepted: 12/08/2023] [Indexed: 12/28/2023]
Abstract
Immunofluorescence microscopy is a widely adopted method for studying meiotic prophase in the nematode model organism, Caenorhabditis elegans . An in-depth examination of specific meiotic processes requires the quantitative analysis of immunofluorescence images, which often involves the segmentation of individual cells or nuclei. Here, we introduce our image analysis pipeline to automate significant portions of this task. This pipeline relies on the powerful deep learning model Cellpose 2.0 to segment cellular structures. To further improve the segmentation accuracy for germline nuclei stained for chromatin or synaptonemal complexes, we retrained the generalist Cellpose model and integrated our data processing pipeline into the easy-to-use Cell-ACDC image analysis software. Our pipeline thus makes deep learning-based segmentation of nuclei in the distal germline of C. elegans accessible for users without coding experience.
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Affiliation(s)
- Cristina Piñeiro López
- Cell Biology and Biophysics, European Molecular Biology Laboratory, Heidelberg, Baden-Württemberg, Germany
| | - Ana Rita Rodrigues Neves
- Cell Biology and Biophysics, European Molecular Biology Laboratory, Heidelberg, Baden-Württemberg, Germany
- Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Ivana Čavka
- Cell Biology and Biophysics, European Molecular Biology Laboratory, Heidelberg, Baden-Württemberg, Germany
- Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Oane Jan Gros
- Cell Biology and Biophysics, European Molecular Biology Laboratory, Heidelberg, Baden-Württemberg, Germany
| | - Simone Köhler
- Cell Biology and Biophysics, European Molecular Biology Laboratory, Heidelberg, Baden-Württemberg, Germany
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7
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Abstract
The raison d'être of meiosis is shuffling of genetic information via Mendelian segregation and, within individual chromosomes, by DNA crossing-over. These outcomes are enabled by a complex cellular program in which interactions between homologous chromosomes play a central role. We first provide a background regarding the basic principles of this program. We then summarize the current understanding of the DNA events of recombination and of three processes that involve whole chromosomes: homolog pairing, crossover interference, and chiasma maturation. All of these processes are implemented by direct physical interaction of recombination complexes with underlying chromosome structures. Finally, we present convergent lines of evidence that the meiotic program may have evolved by coupling of this interaction to late-stage mitotic chromosome morphogenesis.
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Affiliation(s)
- Denise Zickler
- Institute for Integrative Biology of the Cell (I2BC), Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Nancy Kleckner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA;
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8
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Gordon SG, Rog O. Building the synaptonemal complex: Molecular interactions between the axis and the central region. PLoS Genet 2023; 19:e1010822. [PMID: 37471284 PMCID: PMC10359014 DOI: 10.1371/journal.pgen.1010822] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/22/2023] Open
Abstract
The successful delivery of genetic material to gametes requires tightly regulated interactions between the parental chromosomes. Central to this regulation is a conserved chromosomal interface called the synaptonemal complex (SC), which brings the parental chromosomes in close proximity along their length. While many of its components are known, the interfaces that mediate the assembly of the SC remain a mystery. Here, we survey findings from different model systems while focusing on insight gained in the nematode C. elegans. We synthesize our current understanding of the structure, dynamics, and biophysical properties of the SC and propose mechanisms for SC assembly.
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Affiliation(s)
- Spencer G. Gordon
- School of Biological Sciences and Center for Cell and Genome Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Ofer Rog
- School of Biological Sciences and Center for Cell and Genome Sciences, University of Utah, Salt Lake City, Utah, United States of America
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9
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Tabara H, Mitani S, Mochizuki M, Kohara Y, Nagata K. A small RNA system ensures accurate homologous pairing and unpaired silencing of meiotic chromosomes. EMBO J 2023; 42:e105002. [PMID: 37078421 PMCID: PMC10233376 DOI: 10.15252/embj.2020105002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 03/31/2023] [Accepted: 04/04/2023] [Indexed: 04/21/2023] Open
Abstract
During meiosis, chromosomes with homologous partners undergo synaptonemal complex (SC)-mediated pairing, while the remaining unpaired chromosomes are heterochromatinized through unpaired silencing. Mechanisms underlying homolog recognition during SC formation are still unclear. Here, we show that the Caenorhabditis elegans Argonaute proteins, CSR-1 and its paralog CSR-2, interacting with 22G-RNAs, are required for synaptonemal complex formation with accurate homology. CSR-1 in nuclei and meiotic cohesin, constituting the SC lateral elements, were associated with nonsimple DNA repeats, including minisatellites and transposons, and weakly associated with coding genes. CSR-1-associated CeRep55 minisatellites were expressing 22G-RNAs and long noncoding (lnc) RNAs that colocalized with synaptonemal complexes on paired chromosomes and with cohesin regions of unpaired chromosomes. CeRep55 multilocus deletions reduced the efficiencies of homologous pairing and unpaired silencing, which were supported by the csr-1 activity. Moreover, CSR-1 and CSR-2 were required for proper heterochromatinization of unpaired chromosomes. These findings suggest that CSR-1 and CSR-2 play crucial roles in homology recognition, achieving accurate SC formation between chromosome pairs and condensing unpaired chromosomes by targeting repeat-derived lncRNAs.
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Affiliation(s)
- Hiroaki Tabara
- Advanced Genomics CenterNational Institute of GeneticsShizuokaJapan
- Tokyo Women's Medical UniversityTokyoJapan
- Faculty of MedicineUniversity of TsukubaIbarakiJapan
| | | | | | - Yuji Kohara
- Advanced Genomics CenterNational Institute of GeneticsShizuokaJapan
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10
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Almanzar DE, Gordon SG, Bristow C, Hamrick A, von Diezmann L, Liu H, Rog O. Meiotic DNA exchanges in C. elegans are promoted by proximity to the synaptonemal complex. Life Sci Alliance 2023; 6:e202301906. [PMID: 36697255 PMCID: PMC9877436 DOI: 10.26508/lsa.202301906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 01/10/2023] [Accepted: 01/11/2023] [Indexed: 01/27/2023] Open
Abstract
During meiosis, programmed double-strand DNA breaks are repaired to form exchanges between the parental chromosomes called crossovers. Chromosomes lacking a crossover fail to segregate accurately into the gametes, leading to aneuploidy. In addition to engaging the homolog, crossover formation requires the promotion of exchanges, rather than non-exchanges, as repair products. However, the mechanism underlying this meiosis-specific preference is not fully understood. Here, we study the regulation of meiotic sister chromatid exchanges in Caenorhabditis elegans by direct visualization. We find that a conserved chromosomal interface that promotes exchanges between the parental chromosomes, the synaptonemal complex, can also promote exchanges between the sister chromatids. In both cases, exchanges depend on the recruitment of the same set of pro-exchange factors to repair sites. Surprisingly, although the synaptonemal complex usually assembles between the two DNA molecules undergoing an exchange, its activity does not rely on a specific chromosome conformation. This suggests that the synaptonemal complex regulates exchanges-both crossovers and sister exchanges-by establishing a nuclear domain conducive to nearby recruitment of exchange-promoting factors.
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Affiliation(s)
- David E Almanzar
- School of Biological Sciences and Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT, USA
| | - Spencer G Gordon
- School of Biological Sciences and Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT, USA
| | - Chloe Bristow
- School of Biological Sciences and Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT, USA
| | - Antonia Hamrick
- School of Biological Sciences and Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT, USA
| | - Lexy von Diezmann
- School of Biological Sciences and Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT, USA
| | - Hanwenheng Liu
- School of Biological Sciences and Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT, USA
| | - Ofer Rog
- School of Biological Sciences and Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT, USA
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11
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A cryo-fixation protocol to study the structure of the synaptonemal complex. Chromosome Res 2022; 30:385-400. [PMID: 35486207 DOI: 10.1007/s10577-022-09689-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 03/08/2022] [Accepted: 03/28/2022] [Indexed: 01/25/2023]
Abstract
Genetic variability in sexually reproducing organisms results from an exchange of genetic material between homologous chromosomes. The genetic exchange mechanism is dependent on the synaptonemal complex (SC), a protein structure localized between the homologous chromosomes. The current structural models of the mammalian SC are based on electron microscopy, superresolution, and expansion microscopy studies using chemical fixatives and sample dehydration of gonads, which are methodologies known to produce structural artifacts. To further analyze the structure of the SC, without chemical fixation, we have adapted a cryo-fixation method for electron microscopy where pachytene cells are isolated from mouse testis by FACS, followed by cryo-fixation, cryo-substitution, and electron tomography. In parallel, we performed conventional chemical fixation and electron tomography on mouse seminiferous tubules to compare the SC structure obtained with the two fixation methods. We found several differences in the structure and organization of the SC in cryo-fixed samples when compared to chemically preserved samples. We found the central region of the SC to be wider and the transverse filaments to be more densely packed in the central region of the SC.
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12
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Čavka I, Power RM, Walsh D, Zimmermann T, Köhler S. Super-Resolution Microscopy of the Synaptonemal Complex within the Caenorhabditis elegans Germline. J Vis Exp 2022:10.3791/64363. [PMID: 36190293 PMCID: PMC7614930 DOI: 10.3791/64363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023] Open
Abstract
During meiosis, homologous chromosomes must recognize and adhere to one another to allow for their correct segregation. One of the key events that secures the interaction of homologous chromosomes is the assembly of the synaptonemal complex (SC) in meiotic prophase I. Even though there is little sequence homology between protein components within the SC among different species, the general structure of the SC has been highly conserved during evolution. In electron micrographs, the SC appears as a tripartite, ladder-like structure composed of lateral elements or axes, transverse filaments, and a central element. However, precisely identifying the localization of individual components within the complex by electron microscopy to determine the molecular structure of the SC remains challenging. By contrast, fluorescence microscopy allows for the identification of individual protein components within the complex. However, since the SC is only ~100 nm wide, its substructure cannot be resolved by diffraction-limited conventional fluorescence microscopy. Thus, determining the molecular architecture of the SC requires super-resolution light microscopy techniques such as structured illumination microscopy (SIM), stimulated-emission depletion (STED) microscopy, or single-molecule localization microscopy (SMLM). To maintain the structure and interactions of individual components within the SC, it is important to observe the complex in an environment that is close to its native environment in the germ cells. Therefore, we demonstrate an immunohistochemistry and imaging protocol that enables the study of the substructure of the SC in intact, extruded Caenorhabditis elegans germline tissue with SMLM and STED microscopy. Directly fixing the tissue to the coverslip reduces the movement of the samples during imaging and minimizes aberrations in the sample to achieve the high resolution necessary to visualize the substructure of the SC in its biological context.
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Affiliation(s)
- Ivana Čavka
- Cell Biology and Biophysics, European Molecular Biology Laboratory; Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences
| | - Rory M Power
- EMBL Imaging Centre, European Molecular Biology Laboratory
| | - Dietrich Walsh
- EMBL Imaging Centre, European Molecular Biology Laboratory
| | - Timo Zimmermann
- Cell Biology and Biophysics, European Molecular Biology Laboratory; EMBL Imaging Centre, European Molecular Biology Laboratory;
| | - Simone Köhler
- Cell Biology and Biophysics, European Molecular Biology Laboratory;
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13
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Shah P, Bao Z, Zaidel-Bar R. Visualizing and quantifying molecular and cellular processes in C. elegans using light microscopy. Genetics 2022; 221:6619563. [PMID: 35766819 DOI: 10.1093/genetics/iyac068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 04/14/2022] [Indexed: 11/14/2022] Open
Abstract
Light microscopes are the cell and developmental biologists' "best friend", providing a means to see structures and follow dynamics from the protein to the organism level. A huge advantage of C. elegans as a model organism is its transparency, which coupled with its small size means that nearly every biological process can be observed and measured with the appropriate probe and light microscope. Continuous improvement in microscope technologies along with novel genome editing techniques to create transgenic probes have facilitated the development and implementation of a dizzying array of methods for imaging worm embryos, larvae and adults. In this review we provide an overview of the molecular and cellular processes that can be visualized in living worms using light microscopy. A partial inventory of fluorescent probes and techniques successfully used in worms to image the dynamics of cells, organelles, DNA, and protein localization and activity is followed by a practical guide to choosing between various imaging modalities, including widefield, confocal, lightsheet, and structured illumination microscopy. Finally, we discuss the available tools and approaches, including machine learning, for quantitative image analysis tasks, such as colocalization, segmentation, object tracking, and lineage tracing. Hopefully, this review will inspire worm researchers who have not yet imaged their worms to begin, and push those who are imaging to go faster, finer, and longer.
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Affiliation(s)
- Pavak Shah
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles 90095, USA
| | - Zhirong Bao
- Developmental Biology Program, Sloan Kettering Institute, New York, New York 10065, USA
| | - Ronen Zaidel-Bar
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
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14
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Li Y, Shi W, Liu S, Cavka I, Wu YL, Matti U, Wu D, Koehler S, Ries J. Global fitting for high-accuracy multi-channel single-molecule localization. Nat Commun 2022; 13:3133. [PMID: 35668089 PMCID: PMC9170706 DOI: 10.1038/s41467-022-30719-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/16/2022] [Indexed: 11/09/2022] Open
Abstract
Multi-channel detection in single-molecule localization microscopy greatly increases information content for various biological applications. Here, we present globLoc, a graphics processing unit based global fitting algorithm with flexible PSF modeling and parameter sharing, to extract maximum information from multi-channel single molecule data. As signals in multi-channel data are highly correlated, globLoc links parameters such as 3D coordinates or photon counts across channels, improving localization precision and robustness. We show, both in simulations and experiments, that global fitting can substantially improve the 3D localization precision for biplane and 4Pi single-molecule localization microscopy and color assignment for ratiometric multicolor imaging.
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Affiliation(s)
- Yiming Li
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, 518055, China. .,European Molecular Biology Laboratory, Cell Biology and Biophysics, 69117, Heidelberg, Germany.
| | - Wei Shi
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Sheng Liu
- European Molecular Biology Laboratory, Cell Biology and Biophysics, 69117, Heidelberg, Germany
| | - Ivana Cavka
- European Molecular Biology Laboratory, Cell Biology and Biophysics, 69117, Heidelberg, Germany.,Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Yu-Le Wu
- European Molecular Biology Laboratory, Cell Biology and Biophysics, 69117, Heidelberg, Germany.,Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Ulf Matti
- European Molecular Biology Laboratory, Cell Biology and Biophysics, 69117, Heidelberg, Germany
| | - Decheng Wu
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Simone Koehler
- European Molecular Biology Laboratory, Cell Biology and Biophysics, 69117, Heidelberg, Germany
| | - Jonas Ries
- European Molecular Biology Laboratory, Cell Biology and Biophysics, 69117, Heidelberg, Germany.
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15
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Mytlis A, Kumar V, Qiu T, Deis R, Hart N, Levy K, Masek M, Shawahny A, Ahmad A, Eitan H, Nather F, Adar-Levor S, Birnbaum RY, Elia N, Bachmann-Gagescu R, Roy S, Elkouby YM. Control of meiotic chromosomal bouquet and germ cell morphogenesis by the zygotene cilium. Science 2022; 376:eabh3104. [PMID: 35549308 DOI: 10.1126/science.abh3104] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A hallmark of meiosis is chromosomal pairing, which requires telomere tethering and rotation on the nuclear envelope via microtubules, driving chromosome homology searches. Telomere pulling toward the centrosome forms the "zygotene chromosomal bouquet". Here, we identified the "zygotene cilium" in oocytes. This cilium provides a cable system for the bouquet machinery, extending throughout the germline cyst. Using zebrafish mutants and live manipulations, we demonstrate that the cilium anchors the centrosome to counterbalance telomere pulling. The cilium is essential for bouquet and synaptonemal complex formation, oogenesis, ovarian development, and fertility. Thus, a cilium represents a conserved player in zebrafish and mouse meiosis, which sheds light on reproductive aspects in ciliopathies, and suggests that cilia can control chromosomal dynamics.
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Affiliation(s)
- Avishag Mytlis
- Department of Developmental Biology and Cancer Research, Hebrew University of Jerusalem Faculty of Medicine, Ein-Kerem Campus, Jerusalem 9112102, Israel.,Institute for Medical Research-Israel-Canada (IMRIC), Ein-Kerem Campus, Jerusalem 9112102, Israel
| | - Vineet Kumar
- Department of Developmental Biology and Cancer Research, Hebrew University of Jerusalem Faculty of Medicine, Ein-Kerem Campus, Jerusalem 9112102, Israel.,Institute for Medical Research-Israel-Canada (IMRIC), Ein-Kerem Campus, Jerusalem 9112102, Israel
| | - Tao Qiu
- Institute of Molecular and Cell Biology, Proteos, 138673 Singapore
| | - Rachael Deis
- Department of Developmental Biology and Cancer Research, Hebrew University of Jerusalem Faculty of Medicine, Ein-Kerem Campus, Jerusalem 9112102, Israel.,Institute for Medical Research-Israel-Canada (IMRIC), Ein-Kerem Campus, Jerusalem 9112102, Israel
| | - Neta Hart
- Department of Developmental Biology and Cancer Research, Hebrew University of Jerusalem Faculty of Medicine, Ein-Kerem Campus, Jerusalem 9112102, Israel.,Institute for Medical Research-Israel-Canada (IMRIC), Ein-Kerem Campus, Jerusalem 9112102, Israel
| | - Karine Levy
- Department of Developmental Biology and Cancer Research, Hebrew University of Jerusalem Faculty of Medicine, Ein-Kerem Campus, Jerusalem 9112102, Israel.,Institute for Medical Research-Israel-Canada (IMRIC), Ein-Kerem Campus, Jerusalem 9112102, Israel
| | - Markus Masek
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland.,Institute of Medical Genetics, University of Zurich, 8952 Schlieren, Switzerland
| | - Amal Shawahny
- Department of Developmental Biology and Cancer Research, Hebrew University of Jerusalem Faculty of Medicine, Ein-Kerem Campus, Jerusalem 9112102, Israel.,Institute for Medical Research-Israel-Canada (IMRIC), Ein-Kerem Campus, Jerusalem 9112102, Israel
| | - Adam Ahmad
- Department of Developmental Biology and Cancer Research, Hebrew University of Jerusalem Faculty of Medicine, Ein-Kerem Campus, Jerusalem 9112102, Israel.,Institute for Medical Research-Israel-Canada (IMRIC), Ein-Kerem Campus, Jerusalem 9112102, Israel
| | - Hagai Eitan
- Department of Developmental Biology and Cancer Research, Hebrew University of Jerusalem Faculty of Medicine, Ein-Kerem Campus, Jerusalem 9112102, Israel.,Institute for Medical Research-Israel-Canada (IMRIC), Ein-Kerem Campus, Jerusalem 9112102, Israel
| | - Farouq Nather
- Department of Developmental Biology and Cancer Research, Hebrew University of Jerusalem Faculty of Medicine, Ein-Kerem Campus, Jerusalem 9112102, Israel.,Institute for Medical Research-Israel-Canada (IMRIC), Ein-Kerem Campus, Jerusalem 9112102, Israel
| | - Shai Adar-Levor
- Departments of Life Sciences, Ben-Gurion University of the Negev, Beer Shave 84105, Israel
| | - Ramon Y Birnbaum
- Departments of Life Sciences, Ben-Gurion University of the Negev, Beer Shave 84105, Israel
| | - Natalie Elia
- Departments of Life Sciences, Ben-Gurion University of the Negev, Beer Shave 84105, Israel
| | - Ruxandra Bachmann-Gagescu
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland.,Institute of Medical Genetics, University of Zurich, 8952 Schlieren, Switzerland
| | - Sudipto Roy
- Institute of Molecular and Cell Biology, Proteos, 138673 Singapore.,Department of Biological Sciences, National University of Singapore, 117543 Singapore.,Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, 119288 Singapore
| | - Yaniv M Elkouby
- Department of Developmental Biology and Cancer Research, Hebrew University of Jerusalem Faculty of Medicine, Ein-Kerem Campus, Jerusalem 9112102, Israel.,Institute for Medical Research-Israel-Canada (IMRIC), Ein-Kerem Campus, Jerusalem 9112102, Israel
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16
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Functions and Regulation of Meiotic HORMA-Domain Proteins. Genes (Basel) 2022; 13:genes13050777. [PMID: 35627161 PMCID: PMC9141381 DOI: 10.3390/genes13050777] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/20/2022] [Accepted: 04/22/2022] [Indexed: 11/20/2022] Open
Abstract
During meiosis, homologous chromosomes must recognize, pair, and recombine with one another to ensure the formation of inter-homologue crossover events, which, together with sister chromatid cohesion, promote correct chromosome orientation on the first meiotic spindle. Crossover formation requires the assembly of axial elements, proteinaceous structures that assemble along the length of each chromosome during early meiosis, as well as checkpoint mechanisms that control meiotic progression by monitoring pairing and recombination intermediates. A conserved family of proteins defined by the presence of a HORMA (HOp1, Rev7, MAd2) domain, referred to as HORMADs, associate with axial elements to control key events of meiotic prophase. The highly conserved HORMA domain comprises a flexible safety belt sequence, enabling it to adopt at least two of the following protein conformations: one closed, where the safety belt encircles a small peptide motif present within an interacting protein, causing its topological entrapment, and the other open, where the safety belt is reorganized and no interactor is trapped. Although functional studies in multiple organisms have revealed that HORMADs are crucial regulators of meiosis, the mechanisms by which HORMADs implement key meiotic events remain poorly understood. In this review, we summarize protein complexes formed by HORMADs, discuss their roles during meiosis in different organisms, draw comparisons to better characterize non-meiotic HORMADs (MAD2 and REV7), and highlight possible areas for future research.
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17
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Abstract
Super-resolution microscopy techniques, and specifically single-molecule localization microscopy (SMLM), are approaching nanometer resolution inside cells and thus have great potential to complement structural biology techniques such as electron microscopy for structural cell biology. In this review, we introduce the different flavors of super-resolution microscopy, with a special emphasis on SMLM and MINFLUX (minimal photon flux). We summarize recent technical developments that pushed these localization-based techniques to structural scales and review the experimental conditions that are key to obtaining data of the highest quality. Furthermore, we give an overview of different analysis methods and highlight studies that used SMLM to gain structural insights into biologically relevant molecular machines. Ultimately, we give our perspective on what is needed to push the resolution of these techniques even further and to apply them to investigating dynamic structural rearrangements in living cells. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Sheng Liu
- Cell Biology & Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany;
| | - Philipp Hoess
- Cell Biology & Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany;
| | - Jonas Ries
- Cell Biology & Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany;
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18
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Gu Y, Desai A, Corbett KD. Evolutionary Dynamics and Molecular Mechanisms of HORMA Domain Protein Signaling. Annu Rev Biochem 2022; 91:541-569. [PMID: 35041460 DOI: 10.1146/annurev-biochem-090920-103246] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Controlled assembly and disassembly of multi-protein complexes is central to cellular signaling. Proteins of the widespread and functionally diverse HORMA family nucleate assembly of signaling complexes by binding short peptide motifs through a distinctive safety-belt mechanism. HORMA proteins are now understood as key signaling proteins across kingdoms, serving as infection sensors in a bacterial immune system and playing central roles in eukaryotic cell cycle, genome stability, sexual reproduction, and cellular homeostasis pathways. Here, we describe how HORMA proteins' unique ability to adopt multiple conformational states underlies their functions in these diverse contexts. We also outline how a dedicated AAA+ ATPase regulator, Pch2/TRIP13, manipulates HORMA proteins' conformational states to activate or inactivate signaling in different cellular contexts. The emergence of Pch2/TRIP13 as a lynchpin for HORMA protein action in multiple genome-maintenance pathways accounts for its frequent misregulation in human cancers and highlights TRIP13 as a novel therapeutic target. Expected final online publication date for the Annual Review of Biochemistry, Volume 91 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Yajie Gu
- Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, California, USA;
| | - Arshad Desai
- Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, California, USA; .,Section of Cell & Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, California, USA.,Ludwig Institute for Cancer Research, San Diego Branch, La Jolla, California, USA
| | - Kevin D Corbett
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, USA
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19
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Yu CCJ, Orozco Cosio DM, Boyden ES. ExCel: Super-Resolution Imaging of C. elegans with Expansion Microscopy. Methods Mol Biol 2022; 2468:141-203. [PMID: 35320565 PMCID: PMC10194579 DOI: 10.1007/978-1-0716-2181-3_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Studies of C. elegans will benefit from a powerful method for super-resolution imaging of proteins and mRNAs at any 3-D locations throughout the entire animal. Conventional methods of super-resolution imaging in C. elegans, such as STORM, PALM, SR-SIM and STED, are limited by imaging depths that are insufficient to map the entire depth of adult worms, and involve hardware that may not be accessible to all labs. We recently developed expansion of C. elegans (ExCel), a method for physically magnifying fixed whole animals of C. elegans with high isotropy, which provides effective resolutions finer than the diffraction limit, across the entire animal, on conventional confocal microscopes. In this chapter, we present a family of three detailed ExCel protocols. The standard ExCel protocol features simultaneous readout of diverse molecules (fluorescent proteins, RNA, DNA, and general anatomy), all at ~70 nm resolution (~3.5× linear expansion). The epitope-preserving ExCel protocol enables imaging of endogenous proteins with off-the-shelf antibodies, at a ~ 100 nm resolution (~2.8× linear expansion). The iterative ExCel protocol allows readout of fluorescent proteins at ~25 nm resolution (~20× linear expansion). The protocols described here comprise a versatile toolbox for super-resolution imaging of C. elegans.
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Affiliation(s)
- Chih-Chieh Jay Yu
- McGovern Institute for Brain Research and Koch Institute, MIT, Cambridge, MA, USA
- Department of Biological Engineering, MIT, Cambridge, MA, USA
| | - Danielle M Orozco Cosio
- McGovern Institute for Brain Research and Koch Institute, MIT, Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Edward S Boyden
- McGovern Institute for Brain Research and Koch Institute, MIT, Cambridge, MA, USA.
- Department of Biological Engineering, MIT, Cambridge, MA, USA.
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA.
- Howard Hughes Medical Institute, Cambridge, MA, USA.
- Department of Media Arts and Sciences, MIT, Cambridge, MA, USA.
- K Lisa Yang Center for Bionics, and Center for Neurobiological Engineering, MIT, Cambridge, MA, USA.
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20
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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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21
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Abstract
The specialized two-stage meiotic cell division program halves a cell's chromosome complement in preparation for sexual reproduction. This reduction in ploidy requires that in meiotic prophase, each pair of homologous chromosomes (homologs) identify one another and form physical links through DNA recombination. Here, we review recent advances in understanding the complex morphological changes that chromosomes undergo during meiotic prophase to promote homolog identification and crossing over. We focus on the structural maintenance of chromosomes (SMC) family cohesin complexes and the meiotic chromosome axis, which together organize chromosomes and promote recombination. We then discuss the architecture and dynamics of the conserved synaptonemal complex (SC), which assembles between homologs and mediates local and global feedback to ensure high fidelity in meiotic recombination. Finally, we discuss exciting new advances, including mechanisms for boosting recombination on particular chromosomes or chromosomal domains and the implications of a new liquid crystal model for SC assembly and structure. Expected final online publication date for the Annual Review of Genetics, Volume 55 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Sarah N Ur
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093, USA; ,
| | - Kevin D Corbett
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093, USA; , .,Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
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22
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Cohen SM, Le HH, Sternberg PW. A Mutation of lips-6 in C. elegans. MICROPUBLICATION BIOLOGY 2021; 2021:10.17912/micropub.biology.000419. [PMID: 34258545 PMCID: PMC8271349 DOI: 10.17912/micropub.biology.000419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/03/2021] [Accepted: 07/05/2021] [Indexed: 11/09/2022]
Abstract
The lips-6 gene encodes a putative lipase that plays a role in adult starvation response through a pathway that is parallel to the dauer pathway in larval Caenorhabditis elegans worms. We created a mutation of lips-6 to study its effects on lifespan and the ascaroside profile. We found that lips-6 had a wild-type lifespan and a wild-type ascaroside profile. These results suggest that the lips-6 gene plays a minimal role in C. elegans lifespan biology and does not affect the ascaroside profile until it is specifically activated by starvation in adult worms.
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Affiliation(s)
- Sarah M Cohen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Henry H Le
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Paul W Sternberg
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA,
Correspondence to: Paul W Sternberg ()
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23
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von Diezmann L, Rog O. Single-Molecule Tracking of Chromatin-Associated Proteins in the C. elegans Gonad. J Phys Chem B 2021; 125:6162-6170. [PMID: 34097417 DOI: 10.1021/acs.jpcb.1c03040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biomolecules are distributed within cells by molecular-scale diffusion and binding events that are invisible in standard fluorescence microscopy. These molecular search kinetics are key to understanding nuclear signaling and chromosome organization and can be directly observed by single-molecule tracking microscopy. Here, we report a method to track individual proteins within intact C. elegans gonads and apply it to study the molecular dynamics of the axis, a proteinaceous backbone that organizes meiotic chromosomes. Using either fluorescent proteins or enzymatically ligated dyes, we obtain multisecond trajectories with a localization precision of 15-25 nm in nuclei actively undergoing meiosis. Correlation with a reference channel allows for accurate measurement of protein dynamics, compensating for movements of the nuclei and chromosomes within the gonad. We find that axis proteins exhibit either static binding to chromatin or free diffusion in the nucleoplasm, and we separately quantify the motion parameters of these distinct populations. Freely diffusing axis proteins selectively explore chromatin-rich regions, suggesting they are circumventing the central phase-separated region of the nucleus. This work demonstrates that single-molecule microscopy can infer nanoscale-resolution dynamics within living tissue, expanding the possible applications of this approach.
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24
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Grey C, de Massy B. Chromosome Organization in Early Meiotic Prophase. Front Cell Dev Biol 2021; 9:688878. [PMID: 34150782 PMCID: PMC8209517 DOI: 10.3389/fcell.2021.688878] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/10/2021] [Indexed: 12/17/2022] Open
Abstract
One of the most fascinating aspects of meiosis is the extensive reorganization of the genome at the prophase of the first meiotic division (prophase I). The first steps of this reorganization are observed with the establishment of an axis structure, that connects sister chromatids, from which emanate arrays of chromatin loops. This axis structure, called the axial element, consists of various proteins, such as cohesins, HORMA-domain proteins, and axial element proteins. In many organisms, axial elements are required to set the stage for efficient sister chromatid cohesion and meiotic recombination, necessary for the recognition of the homologous chromosomes. Here, we review the different actors involved in axial element formation in Saccharomyces cerevisiae and in mouse. We describe the current knowledge of their localization pattern during prophase I, their functional interdependence, their role in sister chromatid cohesion, loop axis formation, homolog pairing before meiotic recombination, and recombination. We also address further challenges that need to be resolved, to fully understand the interplay between the chromosome structure and the different molecular steps that take place in early prophase I, which lead to the successful outcome of meiosis I.
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Affiliation(s)
- Corinne Grey
- Institut de Génétique Humaine, Centre National de la Recherche Scientifique, Université de Montpellier, Montpellier, France
| | - Bernard de Massy
- Institut de Génétique Humaine, Centre National de la Recherche Scientifique, Université de Montpellier, Montpellier, France
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25
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Abstract
The formation of crossovers between homologous chromosomes is key to sexual reproduction. In most species, crossovers are spaced further apart than would be expected if they formed independently, a phenomenon termed crossover interference. Despite more than a century of study, the molecular mechanisms implementing crossover interference remain a subject of active debate. Recent findings of how signaling proteins control the formation of crossovers and about the interchromosomal interface in which crossovers form offer new insights into this process. In this Review, we present a cell biological and biophysical perspective on crossover interference, summarizing the evidence that links interference to the spatial, dynamic, mechanical and molecular properties of meiotic chromosomes. We synthesize this physical understanding in the context of prevailing mechanistic models that aim to explain how crossover interference is implemented.
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Affiliation(s)
- Lexy von Diezmann
- Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT 84112, USA.,School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Ofer Rog
- Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT 84112, USA.,School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
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26
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Ding DQ, Matsuda A, Okamasa K, Hiraoka Y. Linear elements are stable structures along the chromosome axis in fission yeast meiosis. Chromosoma 2021; 130:149-162. [PMID: 33825974 PMCID: PMC8426239 DOI: 10.1007/s00412-021-00757-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 11/22/2022]
Abstract
The structure of chromosomes dramatically changes upon entering meiosis to ensure the successful progression of meiosis-specific events. During this process, a multilayer proteinaceous structure called a synaptonemal complex (SC) is formed in many eukaryotes. However, in the fission yeast Schizosaccharomyces pombe, linear elements (LinEs), which are structures related to axial elements of the SC, form on the meiotic cohesin-based chromosome axis. The structure of LinEs has been observed using silver-stained electron micrographs or in immunofluorescence-stained spread nuclei. However, the fine structure of LinEs and their dynamics in intact living cells remain to be elucidated. In this study, we performed live cell imaging with wide-field fluorescence microscopy as well as 3D structured illumination microscopy (3D-SIM) of the core components of LinEs (Rec10, Rec25, Rec27, Mug20) and a linE-binding protein Hop1. We found that LinEs form along the chromosome axis and elongate during meiotic prophase. 3D-SIM microscopy revealed that Rec10 localized to meiotic chromosomes in the absence of other LinE proteins, but shaped into LinEs only in the presence of all three other components, the Rec25, Rec27, and Mug20. Elongation of LinEs was impaired in double-strand break-defective rec12− cells. The structure of LinEs persisted after treatment with 1,6-hexanediol and showed slow fluorescence recovery from photobleaching. These results indicate that LinEs are stable structures resembling axial elements of the SC.
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Affiliation(s)
- Da-Qiao Ding
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan.
| | - Atsushi Matsuda
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan
| | - Kasumi Okamasa
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan
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27
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Mytlis A, Elkouby YM. Live and Time-Lapse Imaging of Early Oogenesis and Meiotic Chromosomal Dynamics in Cultured Juvenile Zebrafish Ovaries. Methods Mol Biol 2021; 2218:137-155. [PMID: 33606229 DOI: 10.1007/978-1-0716-0970-5_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Oocyte production is crucial for sexual reproduction. Recent findings in zebrafish and other established model organisms emphasize that the early steps of oogenesis involve the coordination of simultaneous and tightly sequential processes across cellular compartments and between sister cells. To fully understand the mechanistic framework of these coordinated processes, cellular and morphological analysis in high temporal resolution is required. Here, we provide a protocol for four-dimensional live time-lapse analysis of cultured juvenile zebrafish ovaries. We describe how multiple-stage oocytes can be simultaneously analyzed in single ovaries, and several ovaries can be processed in single experiments. In addition, we detail adequate conditions for quantitative image acquisition. Finally, we demonstrate that using this protocol, we successfully capture rapid meiotic chromosomal movements in early prophase for the first time in zebrafish oocytes, in four dimensions and in vivo. Our protocol expands the use of the zebrafish as a model system to understand germ cell and ovarian development in postembryonic stages.
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Affiliation(s)
- Avishag Mytlis
- Department of Developmental Biology and Cancer Research, The Hebrew University of Jerusalem, Faculty of Medicine, Institute for Medical Research - Israel-Canada (IMRIC), Jerusalem, Israel
| | - Yaniv M Elkouby
- Department of Developmental Biology and Cancer Research, The Hebrew University of Jerusalem, Faculty of Medicine, Institute for Medical Research - Israel-Canada (IMRIC), Jerusalem, Israel.
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28
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Abstract
Cohesin helps mediate sister chromatid cohesion, chromosome condensation, DNA repair, and transcription regulation. We exploited proximity-dependent labeling to define the in vivo interactions of cohesin domains with DNA or with other cohesin domains that lie within the same or in different cohesin complexes. Our results suggest that both cohesin's head and hinge domains are proximal to DNA, and cohesin structure is dynamic with differential folding of its coiled coil regions to generate butterfly confirmations. This method also reveals that cohesins form ordered clusters on and off DNA. The levels of cohesin clusters and their distribution on chromosomes are cell cycle-regulated. Cohesin clustering is likely necessary for cohesion maintenance because clustering and maintenance uniquely require the same subset of cohesin domains and the auxiliary cohesin factor Pds5p. These conclusions provide important new mechanistic and biological insights into the architecture of the cohesin complex, cohesin-cohesin interactions, and cohesin's tethering and loop-extruding activities.
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Affiliation(s)
- Siheng Xiang
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Douglas Koshland
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
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29
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Tian H, Billings T, Petkov PM. EWSR1 affects PRDM9-dependent histone 3 methylation and provides a link between recombination hotspots and the chromosome axis protein REC8. Mol Biol Cell 2021; 32:1-14. [PMID: 33175657 PMCID: PMC8098819 DOI: 10.1091/mbc.e20-09-0604] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/29/2020] [Accepted: 11/04/2020] [Indexed: 12/12/2022] Open
Abstract
Meiotic recombination in most mammals requires recombination hotspot activation through the action of the histone 3 Lys-4 and Lys-36 methyltransferase PRDM9 to ensure successful double-strand-break initiation and repair. Here we show that EWSR1, a protein whose role in meiosis was not previously clarified in detail, binds to both PRDM9 and pREC8, a phosphorylated meiosis-specific cohesin, in male meiotic cells. We created a Ewsr1 conditional knockout mouse model to deplete EWSR1 before the onset of meiosis and found that absence of EWSR1 causes meiotic arrest with decreased histone trimethylation at meiotic hotspots, impaired DNA double-strand-break repair, and reduced crossover number. Our results demonstrate that EWSR1 is essential for promoting PRDM9-dependent histone methylation and normal meiotic progress, possibly by facilitating the linking between PRDM9-bound hotspots and the nascent chromosome axis through its component cohesin pREC8.
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Affiliation(s)
- Hui Tian
- The Jackson Laboratory, Bar Harbor, ME 04609
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30
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Clark JN, Prajapati G, Aldaco FK, Sokolich TJ, Keung SS, Austin SP, Valdés ÁA, LaMunyon CW. Functionally non-redundant paralogs spe-47 and spe-50 encode FB-MO associated proteins and interact with him-8. PLoS One 2020; 15:e0230939. [PMID: 33382704 PMCID: PMC7774929 DOI: 10.1371/journal.pone.0230939] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 12/10/2020] [Indexed: 11/25/2022] Open
Abstract
The activation of C. elegans spermatids to crawling spermatozoa is affected by a number of genes including spe-47. Here, we investigate a paralog to spe-47: spe-50, which has a highly conserved sequence and expression, but which is not functionally redundant to spe-47. Phylogenetic analysis indicates that the duplication event that produced the paralogs occurred prior to the radiation of the Caenorhabditis species included in the analysis, allowing a long period for the paralogs to diverge in function. Furthermore, we observed that knockout mutations in both genes, either alone or together, have little effect on sperm function. However, hermaphrodites harboring both knockout mutations combined with a third mutation in the him-8 gene are nearly self-sterile due to a sperm defect, even though they have numerous apparently normal sperm within their spermathecae. We suggest that the sperm in these triple mutants are defective in fusing with oocytes, and that the effect of the him-8 mutation is unclear but likely due to its direct or indirect effect on local chromatin structure and function.
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Affiliation(s)
- Jessica N. Clark
- Department of Biological Sciences, Cal Poly Pomona, Pomona, California, United States of America
| | - Gaurav Prajapati
- Department of Biological Sciences, Cal Poly Pomona, Pomona, California, United States of America
| | - Fermina K. Aldaco
- Department of Biological Sciences, Cal Poly Pomona, Pomona, California, United States of America
| | - Thomas J. Sokolich
- Department of Biological Sciences, Cal Poly Pomona, Pomona, California, United States of America
| | - Steven S. Keung
- Department of Biological Sciences, Cal Poly Pomona, Pomona, California, United States of America
| | - Sarojani P. Austin
- Department of Biological Sciences, Cal Poly Pomona, Pomona, California, United States of America
| | - Ángel A. Valdés
- Department of Biological Sciences, Cal Poly Pomona, Pomona, California, United States of America
| | - Craig W. LaMunyon
- Department of Biological Sciences, Cal Poly Pomona, Pomona, California, United States of America
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31
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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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32
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Das D, Chen SY, Arur S. ERK phosphorylates chromosomal axis component HORMA domain protein HTP-1 to regulate oocyte numbers. SCIENCE ADVANCES 2020; 6:6/44/eabc5580. [PMID: 33127680 PMCID: PMC7608811 DOI: 10.1126/sciadv.abc5580] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 09/18/2020] [Indexed: 05/10/2023]
Abstract
Oocyte numbers, a critical determinant of female reproductive fitness, are highly regulated, yet the mechanisms underlying this regulation remain largely undefined. In the Caenorhabditis elegans gonad, RAS/extracellular signal-regulated kinase (ERK) signaling regulates oocyte numbers; mechanisms are unknown. We show that the RAS/ERK pathway phosphorylates meiotic chromosome axis protein HTP-1 at serine-325 to control chromosome dynamics and regulate oocyte number. Phosphorylated HTP-1(S325) accumulates in vivo in an ERK-dependent manner in early-mid pachytene stage germ cells and is necessary for synaptonemal complex extension and/or maintenance. Lack of HTP-1 phosphorylation leads to asynapsis and persistence of meiotic double-strand breaks, causing delayed meiotic progression and reduced oocyte number. In contrast, early onset of ERK activation causes precocious meiotic progression, resulting in increased oocyte number, which is reversed by removal of HTP-1 phosphorylation. The RAS/ERK/HTP-1 signaling cascade thus functions to monitor formation and maintenance of synapsis for timely resolution of double-strand breaks, oocyte production, and reproductive fitness.
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Affiliation(s)
- Debabrata Das
- 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
| | - Swathi Arur
- Department of Genetics, UT MD Anderson Cancer Center, Houston, TX 77030, USA.
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Agbleke AA, Amitai A, Buenrostro JD, Chakrabarti A, Chu L, Hansen AS, Koenig KM, Labade AS, Liu S, Nozaki T, Ovchinnikov S, Seeber A, Shaban HA, Spille JH, Stephens AD, Su JH, Wadduwage D. Advances in Chromatin and Chromosome Research: Perspectives from Multiple Fields. Mol Cell 2020; 79:881-901. [PMID: 32768408 PMCID: PMC7888594 DOI: 10.1016/j.molcel.2020.07.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 06/12/2020] [Accepted: 07/06/2020] [Indexed: 12/12/2022]
Abstract
Nucleosomes package genomic DNA into chromatin. By regulating DNA access for transcription, replication, DNA repair, and epigenetic modification, chromatin forms the nexus of most nuclear processes. In addition, dynamic organization of chromatin underlies both regulation of gene expression and evolution of chromosomes into individualized sister objects, which can segregate cleanly to different daughter cells at anaphase. This collaborative review shines a spotlight on technologies that will be crucial to interrogate key questions in chromatin and chromosome biology including state-of-the-art microscopy techniques, tools to physically manipulate chromatin, single-cell methods to measure chromatin accessibility, computational imaging with neural networks and analytical tools to interpret chromatin structure and dynamics. In addition, this review provides perspectives on how these tools can be applied to specific research fields such as genome stability and developmental biology and to test concepts such as phase separation of chromatin.
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Affiliation(s)
| | - Assaf Amitai
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jason D Buenrostro
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA
| | - Aditi Chakrabarti
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Lingluo Chu
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Anders S Hansen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Kristen M Koenig
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; JHDSF Program, Harvard University, Cambridge, MA 02138, USA
| | - Ajay S Labade
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA
| | - Sirui Liu
- FAS Division of Science, Harvard University, Cambridge, MA 02138, USA
| | - Tadasu Nozaki
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Sergey Ovchinnikov
- JHDSF Program, Harvard University, Cambridge, MA 02138, USA; FAS Division of Science, Harvard University, Cambridge, MA 02138, USA
| | - Andrew Seeber
- JHDSF Program, Harvard University, Cambridge, MA 02138, USA; Center for Advanced Imaging, Harvard University, Cambridge, MA 02138, USA.
| | - Haitham A Shaban
- Center for Advanced Imaging, Harvard University, Cambridge, MA 02138, USA; Spectroscopy Department, Physics Division, National Research Centre, Dokki, 12622 Cairo, Egypt
| | - Jan-Hendrik Spille
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Andrew D Stephens
- Biology Department, University of Massachusetts, Amherst, Amherst, MA 01003, USA
| | - Jun-Han Su
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Dushan Wadduwage
- JHDSF Program, Harvard University, Cambridge, MA 02138, USA; Center for Advanced Imaging, Harvard University, Cambridge, MA 02138, USA
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34
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Wu YL, Tschanz A, Krupnik L, Ries J. Quantitative Data Analysis in Single-Molecule Localization Microscopy. Trends Cell Biol 2020; 30:837-851. [PMID: 32830013 DOI: 10.1016/j.tcb.2020.07.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/17/2020] [Accepted: 07/20/2020] [Indexed: 12/24/2022]
Abstract
Super-resolution microscopy, and specifically single-molecule localization microscopy (SMLM), is becoming a transformative technology for cell biology, as it allows the study of cellular structures with nanometer resolution. Here, we review a wide range of data analyses approaches for SMLM that extract quantitative information about the distribution, size, shape, spatial organization, and stoichiometry of macromolecular complexes to guide biological interpretation. We present a case study using the nuclear pore complex as an example that highlights the power of combining complementary approaches by identifying its symmetry, ringlike structure, and protein copy number. In face of recent technical and computational advances, this review serves as a guideline for selecting appropriate analysis tools and controls to exploit the potential of SMLM for a wide range of biological questions.
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Affiliation(s)
- Yu-Le Wu
- European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Heidelberg, Germany; Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Aline Tschanz
- European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Heidelberg, Germany; Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Leonard Krupnik
- European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Heidelberg, Germany; Faculty of Chemistry and Earth Sciences, Heidelberg University, Heidelberg, Germany
| | - Jonas Ries
- European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Heidelberg, Germany.
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35
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Woglar A, Yamaya K, Roelens B, Boettiger A, Köhler S, Villeneuve AM. Quantitative cytogenetics reveals molecular stoichiometry and longitudinal organization of meiotic chromosome axes and loops. PLoS Biol 2020; 18:e3000817. [PMID: 32813728 PMCID: PMC7458323 DOI: 10.1371/journal.pbio.3000817] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 08/31/2020] [Accepted: 07/31/2020] [Indexed: 11/18/2022] Open
Abstract
During meiosis, chromosomes adopt a specialized organization involving assembly of a cohesin-based axis along their lengths, with DNA loops emanating from this axis. We applied novel, quantitative, and widely applicable cytogenetic strategies to elucidate the molecular bases of this organization using Caenorhabditis elegans. Analyses of wild-type (WT) chromosomes and de novo circular minichromosomes revealed that meiosis-specific HORMA-domain proteins assemble into cohorts in defined numbers and co-organize the axis together with 2 functionally distinct cohesin complexes (REC-8 and COH-3/4) in defined stoichiometry. We further found that REC-8 cohesins, which load during S phase and mediate sister-chromatid cohesion, usually occur as individual complexes, supporting a model wherein sister cohesion is mediated locally by a single cohesin ring. REC-8 complexes are interspersed in an alternating pattern with cohorts of axis-organizing COH-3/4 complexes (averaging 3 per cohort), which are insufficient to confer cohesion but can bind to individual chromatids, suggesting a mechanism to enable formation of asymmetric sister-chromatid loops. Indeed, immunofluorescence/fluorescence in situ hybridization (immuno-FISH) assays demonstrate frequent asymmetry in genomic content between the loops formed on sister chromatids. We discuss how features of chromosome axis/loop architecture inferred from our data can help to explain enigmatic, yet essential, aspects of the meiotic program.
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Affiliation(s)
- Alexander Woglar
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Kei Yamaya
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Baptiste Roelens
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Alistair Boettiger
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Simone Köhler
- European Molecular Biology Laboratory, Heidelberg, Heidelberg, Germany
| | - Anne M. Villeneuve
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
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36
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Hurlock ME, Čavka I, Kursel LE, Haversat J, Wooten M, Nizami Z, Turniansky R, Hoess P, Ries J, Gall JG, Rog O, Köhler S, Kim Y. Identification of novel synaptonemal complex components in C. elegans. J Cell Biol 2020; 219:e201910043. [PMID: 32211899 PMCID: PMC7199856 DOI: 10.1083/jcb.201910043] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/04/2020] [Accepted: 02/26/2020] [Indexed: 11/22/2022] Open
Abstract
The synaptonemal complex (SC) is a tripartite protein scaffold that forms between homologous chromosomes during meiosis. Although the SC is essential for stable homologue pairing and crossover recombination in diverse eukaryotes, it is unknown how individual components assemble into the highly conserved SC structure. Here we report the biochemical identification of two new SC components, SYP-5 and SYP-6, in Caenorhabditis elegans. SYP-5 and SYP-6 are paralogous to each other and play redundant roles in synapsis, providing an explanation for why these genes have evaded previous genetic screens. Superresolution microscopy reveals that they localize between the chromosome axes and span the width of the SC in a head-to-head manner, similar to the orientation of other known transverse filament proteins. Using genetic redundancy and structure-function analyses to truncate C-terminal tails of SYP-5/6, we provide evidence supporting the role of SC in both limiting and promoting crossover formation.
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Affiliation(s)
| | - Ivana Čavka
- The European Molecular Biology Laboratory, Heidelberg, Germany
| | - Lisa E. Kursel
- School of Biological Sciences, University of Utah, Salt Lake City, UT
| | | | - Matthew Wooten
- Department of Biology, Johns Hopkins University, Baltimore, MD
| | - Zehra Nizami
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD
| | | | - Philipp Hoess
- The European Molecular Biology Laboratory, Heidelberg, Germany
- Collaboration for joint PhD degree between European Molecular Biology Laboratory and Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Jonas Ries
- The European Molecular Biology Laboratory, Heidelberg, Germany
| | - Joseph G. Gall
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD
| | - Ofer Rog
- School of Biological Sciences, University of Utah, Salt Lake City, UT
| | - Simone Köhler
- The European Molecular Biology Laboratory, Heidelberg, Germany
| | - Yumi Kim
- Department of Biology, Johns Hopkins University, Baltimore, MD
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37
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Yu CC(J, Barry NC, Wassie AT, Sinha A, Bhattacharya A, Asano S, Zhang C, Chen F, Hobert O, Goodman MB, Haspel G, Boyden ES. Expansion microscopy of C. elegans. eLife 2020; 9:e46249. [PMID: 32356725 PMCID: PMC7195193 DOI: 10.7554/elife.46249] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 03/30/2020] [Indexed: 12/20/2022] Open
Abstract
We recently developed expansion microscopy (ExM), which achieves nanoscale-precise imaging of specimens at ~70 nm resolution (with ~4.5x linear expansion) by isotropic swelling of chemically processed, hydrogel-embedded tissue. ExM of C. elegans is challenged by its cuticle, which is stiff and impermeable to antibodies. Here we present a strategy, expansion of C. elegans (ExCel), to expand fixed, intact C. elegans. ExCel enables simultaneous readout of fluorescent proteins, RNA, DNA location, and anatomical structures at resolutions of ~65-75 nm (3.3-3.8x linear expansion). We also developed epitope-preserving ExCel, which enables imaging of endogenous proteins stained by antibodies, and iterative ExCel, which enables imaging of fluorescent proteins after 20x linear expansion. We demonstrate the utility of the ExCel toolbox for mapping synaptic proteins, for identifying previously unreported proteins at cell junctions, and for gene expression analysis in multiple individual neurons of the same animal.
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Affiliation(s)
- Chih-Chieh (Jay) Yu
- Department of Biological Engineering, Massachusetts Institute of TechnologyCambridgeUnited States
- Media Lab, Massachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Nicholas C Barry
- Media Lab, Massachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Asmamaw T Wassie
- Department of Biological Engineering, Massachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Anubhav Sinha
- Media Lab, Massachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
- Division of Health Sciences and Technology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Abhishek Bhattacharya
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
| | - Shoh Asano
- Media Lab, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Chi Zhang
- Media Lab, Massachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Fei Chen
- Broad Institute of MIT and HarvardCambridgeUnited States
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
| | - Miriam B Goodman
- Department of Molecular and Cellular Physiology, Stanford UniversityStanfordUnited States
| | - Gal Haspel
- Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University-NewarkNewarkUnited States
- The Brain Research Institute, New Jersey Institute of TechnologyNewarkUnited States
| | - Edward S Boyden
- Department of Biological Engineering, Massachusetts Institute of TechnologyCambridgeUnited States
- Media Lab, Massachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
- Koch Institute, Massachusetts Institute of TechnologyCambridgeUnited States
- Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
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38
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Kim H, Yen L, Wongpalee SP, Kirshner JA, Mehta N, Xue Y, Johnston JB, Burlingame AL, Kim JK, Loparo JJ, Jacobsen SE. The Gene-Silencing Protein MORC-1 Topologically Entraps DNA and Forms Multimeric Assemblies to Cause DNA Compaction. Mol Cell 2020; 75:700-710.e6. [PMID: 31442422 DOI: 10.1016/j.molcel.2019.07.032] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 05/28/2019] [Accepted: 07/23/2019] [Indexed: 12/21/2022]
Abstract
Microrchidia (MORC) ATPases are critical for gene silencing and chromatin compaction in multiple eukaryotic systems, but the mechanisms by which MORC proteins act are poorly understood. Here, we apply a series of biochemical, single-molecule, and cell-based imaging approaches to better understand the function of the Caenorhabditis elegans MORC-1 protein. We find that MORC-1 binds to DNA in a length-dependent but sequence non-specific manner and compacts DNA by forming DNA loops. MORC-1 molecules diffuse along DNA but become static as they grow into foci that are topologically entrapped on DNA. Consistent with the observed MORC-1 multimeric assemblies, MORC-1 forms nuclear puncta in cells and can also form phase-separated droplets in vitro. We also demonstrate that MORC-1 compacts nucleosome templates. These results suggest that MORCs affect genome structure and gene silencing by forming multimeric assemblages to topologically entrap and progressively loop and compact chromatin.
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Affiliation(s)
- HyeongJun Kim
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Department of Physics and Astronomy, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA; Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Linda Yen
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Somsakul P Wongpalee
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Jessica A Kirshner
- Department of Biology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Nicita Mehta
- Department of Biology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Yan Xue
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jonathan B Johnston
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Alma L Burlingame
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - John K Kim
- Department of Biology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Joseph J Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
| | - Steve E Jacobsen
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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39
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Bollschweiler D, Radu L, Joudeh L, Plitzko JM, Henderson RM, Mela I, Pellegrini L. Molecular architecture of the SYCP3 fibre and its interaction with DNA. Open Biol 2019; 9:190094. [PMID: 31615332 PMCID: PMC6833220 DOI: 10.1098/rsob.190094] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The synaptonemal complex (SC) keeps homologous chromosomes in close alignment during meiotic recombination. A hallmark of the SC is the presence of its constituent protein SYCP3 on the chromosome axis. During SC assembly, SYCP3 is deposited on both axes of the homologue pair, forming axial elements that fuse into the lateral element (LE) in the tripartite structure of the mature SC. We have used cryo-electron tomography and atomic force microscopy to study the mechanism of assembly and DNA binding of the SYCP3 fibre. We find that the three-dimensional architecture of the fibre is built on a highly irregular arrangement of SYCP3 molecules displaying very limited local geometry. Interaction between SYCP3 molecules is driven by the intrinsically disordered tails of the protein, with no contact between the helical cores, resulting in a flexible fibre assembly. We demonstrate that the SYCP3 fibre can engage in extensive interactions with DNA, indicative of an efficient mechanism for incorporation of DNA within the fibre. Our findings suggest that SYCP3 deposition on the chromosome axis might take place by polymerization into a fibre that is fastened to the chromosome surface via DNA binding.
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Affiliation(s)
| | - Laura Radu
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Luay Joudeh
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Jürgen M Plitzko
- Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Robert M Henderson
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK
| | - Ioanna Mela
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK
| | - Luca Pellegrini
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
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40
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Cahoon CK, Helm JM, Libuda DE. Synaptonemal Complex Central Region Proteins Promote Localization of Pro-crossover Factors to Recombination Events During Caenorhabditis elegans Meiosis. Genetics 2019; 213:395-409. [PMID: 31431470 PMCID: PMC6781886 DOI: 10.1534/genetics.119.302625] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 08/16/2019] [Indexed: 11/23/2022] Open
Abstract
Crossovers (COs) between homologous chromosomes are critical for meiotic chromosome segregation and form in the context of the synaptonemal complex (SC), a meiosis-specific structure that assembles between aligned homologs. During Caenorhabditis elegans meiosis, central region components of the SC (SYP proteins) are essential to repair double-strand DNA breaks (DSBs) as COs. Here, we investigate the relationships between the SYP proteins and conserved pro-CO factors by examining the immunolocalization of these proteins in meiotic mutants where SYP proteins are absent, reduced, or mislocalized. Although COs do not form in syp null mutants, pro-CO factors COSA-1, MSH-5, and ZHP-3 nevertheless colocalize at DSB-dependent sites during late prophase, reflecting an inherent affinity of these factors for DSB repair sites. In contrast, in mutants where SYP proteins are present but form aggregates or display abnormal synapsis, pro-CO factors consistently track with SYP-1 localization. Further, pro-CO factors usually localize to a single site per SYP-1 structure, even in SYP aggregates or in mutants where the SC forms between sister chromatids, suggesting that CO regulation occurs within these aberrant SC structures. Moreover, we find that the meiotic cohesin REC-8 is required to ensure that SC formation occurs between homologs and not sister chromatids. Taken together, our findings support a model in which SYP proteins promote CO formation by promoting the localization of pro-CO factors to recombination events within an SC compartment, thereby ensuring that pro-CO factors identify a recombination event within an SC structure and that CO maturation occurs only between properly aligned homologous chromosomes.
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Affiliation(s)
- Cori K Cahoon
- Department of Biology, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Jacquellyn M Helm
- Department of Biology, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Diana E Libuda
- Department of Biology, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
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41
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A first genetic portrait of synaptonemal complex variation. PLoS Genet 2019; 15:e1008337. [PMID: 31449519 PMCID: PMC6730954 DOI: 10.1371/journal.pgen.1008337] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 09/06/2019] [Accepted: 07/31/2019] [Indexed: 12/30/2022] Open
Abstract
The synaptonemal complex (SC) is a proteinaceous scaffold required for synapsis and recombination between homologous chromosomes during meiosis. Although the SC has been linked to differences in genome-wide crossover rates, the genetic basis of standing variation in SC structure remains unknown. To investigate the possibility that recombination evolves through changes to the SC, we characterized the genetic architecture of SC divergence on two evolutionary timescales. Applying a novel digital image analysis technique to spermatocyte spreads, we measured total SC length in 9,532 spermatocytes from recombinant offspring of wild-derived mouse strains with differences in this fundamental meiotic trait. Using this large dataset, we identified the first known genomic regions involved in the evolution of SC length. Distinct loci affect total SC length divergence between and within subspecies, with the X chromosome contributing to both. Joint genetic analysis of MLH1 foci—immunofluorescent markers of crossovers—from the same spermatocytes revealed that two of the identified loci also confer differences in the genome-wide recombination rate. Causal mediation analysis suggested that one pleiotropic locus acts early in meiosis to designate crossovers prior to SC assembly, whereas a second locus primarily shapes crossover number through its effect on SC length. One genomic interval shapes the relationship between SC length and recombination rate, likely modulating the strength of crossover interference. Our findings pinpoint SC formation as a key step in the evolution of recombination and demonstrate the power of genetic mapping on standing variation in the context of the recombination pathway. During the first stages of meiosis, the chromosome axes are organized along a protein scaffold in preparation for recombination and their subsequent segregation. This scaffold, known as the synaptonemal complex (SC), is critical for the regular progression of recombination. A complex relationship exists between the organization of the SC, the frequency of recombination, and the likelihood of improper chromosome segregation. In this study, we investigate the genetics of synaptonemal complex variation in the house mouse and connect it with variation in the rate of recombination. We found five loci and several compelling candidate genes responsible for the evolution of synaptonemal complex length within and between mouse subspecies. Several of these loci also affect recombination rate, and our joint analyses of the phenotypes suggest an order by which their effects manifest within the recombination pathway. Our results show that evolution of SC length is crucial to recombination rate divergence. Our work here also demonstrates that genetic analysis of additional meiotic phenotypes can help explain the evolution of recombination, a fundamental evolutionary force.
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42
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Molecular organization of mammalian meiotic chromosome axis revealed by expansion STORM microscopy. Proc Natl Acad Sci U S A 2019; 116:18423-18428. [PMID: 31444302 DOI: 10.1073/pnas.1902440116] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
During prophase I of meiosis, chromosomes become organized as loop arrays around the proteinaceous chromosome axis. As homologous chromosomes physically pair and recombine, the chromosome axis is integrated into the tripartite synaptonemal complex (SC) as this structure's lateral elements (LEs). While the components of the mammalian chromosome axis/LE-including meiosis-specific cohesin complexes, the axial element proteins SYCP3 and SYCP2, and the HORMA domain proteins HORMAD1 and HORMAD2-are known, the molecular organization of these components within the axis is poorly understood. Here, using expansion microscopy coupled with 2-color stochastic optical reconstruction microscopy (STORM) imaging (ExSTORM), we address these issues in mouse spermatocytes at a resolution of 10 to 20 nm. Our data show that SYCP3 and the SYCP2 C terminus, which are known to form filaments in vitro, form a compact core around which cohesin complexes, HORMADs, and the N terminus of SYCP2 are arrayed. Overall, our study provides a detailed structural view of the meiotic chromosome axis, a key organizational and regulatory component of meiotic chromosomes.
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43
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Oblique-plane single-molecule localization microscopy for tissues and small intact animals. Nat Methods 2019; 16:853-857. [PMID: 31427757 DOI: 10.1038/s41592-019-0510-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 05/06/2019] [Indexed: 11/08/2022]
Abstract
Single-molecule localization microscopy (SMLM), while well established for cultured cells, is not yet fully compatible with tissue-scale samples. We introduce single-molecule oblique-plane microscopy (obSTORM), which by directly imaging oblique sections of samples with oblique light-sheet illumination offers a deep and volumetric SMLM platform that is convenient for standard tissue samples and small intact animals. We demonstrate super-resolution imaging at depths of up to 66 µm for cells, Caenorhabditis elegans gonads, Drosophila melanogaster larval brain, mouse retina and brain sections, and whole stickleback fish.
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44
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Yi X, Son S, Ando R, Miyawaki A, Weiss S. Moments reconstruction and local dynamic range compression of high order superresolution optical fluctuation imaging. BIOMEDICAL OPTICS EXPRESS 2019; 10:2430-2445. [PMID: 31149378 PMCID: PMC6524576 DOI: 10.1364/boe.10.002430] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 03/20/2019] [Accepted: 03/22/2019] [Indexed: 05/26/2023]
Abstract
Super-resolution optical fluctuation imaging (SOFI) offers a simple and affordable alternative to other super-resolution (SR) imaging techniques. The theoretical resolution enhancement of SOFI scales linearly with the order of cumulants, while the imaging conditions exhibit less photo-toxicity to the living samples as compared to other SR methods. High order SOFI could, therefore, be a method of choice for dynamic live cell imaging. However, due to the cusp-artifacts and dynamic range expansion of pixel intensities, this promise has not been materialized as of yet. Here we investigated and compared high order moments vs. high order cumulant SOFI reconstructions. We demonstrate that even-order moments reconstructions are intrinsically free of cusp artifacts, allowing for a subsequent deconvolution operation to be performed, hence enhancing the resolution even further. High order moments reconstruction performance was examined for various (simulated) conditions and applied to (experimental) imaging of QD labeled microtubules in fixed cells, and actin stress fiber dynamics in live cells.
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Affiliation(s)
- Xiyu Yi
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Sungho Son
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA
| | - Ryoko Ando
- Laboratory for Cell Function and Dynamics, RIKEN Center for Brain Science, Saitama 351-0198, Japan
| | - Atsushi Miyawaki
- Laboratory for Cell Function and Dynamics, RIKEN Center for Brain Science, Saitama 351-0198, Japan
- Biotechnological Optics Research Team, RIKEN Center for Advanced Photonics, Saitama 351-0198, Japan
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
- Department of Physiology, University of California, Los Angeles, CA 90095, USA
- California Nano Systems Institute, University of California, Los Angeles, CA 90095, USA
- Department of Physics, Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel
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45
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Cahoon CK, Libuda DE. Leagues of their own: sexually dimorphic features of meiotic prophase I. Chromosoma 2019; 128:199-214. [PMID: 30826870 PMCID: PMC6823309 DOI: 10.1007/s00412-019-00692-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 01/28/2019] [Accepted: 02/05/2019] [Indexed: 01/12/2023]
Abstract
Meiosis is a conserved cell division process that is used by sexually reproducing organisms to generate haploid gametes. Males and females produce different end products of meiosis: eggs (females) and sperm (males). In addition, these unique end products demonstrate sex-specific differences that occur throughout meiosis to produce the final genetic material that is packaged into distinct gametes with unique extracellular morphologies and nuclear sizes. These sexually dimorphic features of meiosis include the meiotic chromosome architecture, in which both the lengths of the chromosomes and the requirement for specific meiotic axis proteins being different between the sexes. Moreover, these changes likely cause sex-specific changes in the recombination landscape with the sex that has the longer chromosomes usually obtaining more crossovers. Additionally, epigenetic regulation of meiosis may contribute to sexually dimorphic recombination landscapes. Here we explore the sexually dimorphic features of both the chromosome axis and crossing over for each stage of meiotic prophase I in Mus musculus, Caenorhabditis elegans, and Arabidopsis thaliana. Furthermore, we consider how sex-specific changes in the meiotic chromosome axes and the epigenetic landscape may function together to regulate crossing over in each sex, indicating that the mechanisms controlling crossing over may be different in oogenesis and spermatogenesis.
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Affiliation(s)
- Cori K Cahoon
- Institute of Molecular Biology, Department of Biology, University of Oregon, 1370 Franklin Boulevard, Eugene, OR, 97403-1229, USA
| | - Diana E Libuda
- Institute of Molecular Biology, Department of Biology, University of Oregon, 1370 Franklin Boulevard, Eugene, OR, 97403-1229, USA.
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46
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Breimann L, Preusser F, Preibisch S. Light-microscopy methods in C. elegans research. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.coisb.2018.11.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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47
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West AMV, Rosenberg SC, Ur SN, Lehmer MK, Ye Q, Hagemann G, Caballero I, Usón I, MacQueen AJ, Herzog F, Corbett KD. A conserved filamentous assembly underlies the structure of the meiotic chromosome axis. eLife 2019; 8:e40372. [PMID: 30657449 PMCID: PMC6349405 DOI: 10.7554/elife.40372] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 01/18/2019] [Indexed: 11/30/2022] Open
Abstract
The meiotic chromosome axis plays key roles in meiotic chromosome organization and recombination, yet the underlying protein components of this structure are highly diverged. Here, we show that 'axis core proteins' from budding yeast (Red1), mammals (SYCP2/SYCP3), and plants (ASY3/ASY4) are evolutionarily related and play equivalent roles in chromosome axis assembly. We first identify 'closure motifs' in each complex that recruit meiotic HORMADs, the master regulators of meiotic recombination. We next find that axis core proteins form homotetrameric (Red1) or heterotetrameric (SYCP2:SYCP3 and ASY3:ASY4) coiled-coil assemblies that further oligomerize into micron-length filaments. Thus, the meiotic chromosome axis core in fungi, mammals, and plants shares a common molecular architecture, and likely also plays conserved roles in meiotic chromosome axis assembly and recombination control.
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Affiliation(s)
- Alan MV West
- Biomedical Sciences Graduate ProgramUniversity of California, San DiegoLa JollaUnited States
- Department of Cellular and Molecular MedicineUniversity of California, San DiegoLa JollaUnited States
| | - Scott C Rosenberg
- Department of ChemistryUniversity of California, San DiegoLa JollaUnited States
| | - Sarah N Ur
- Biomedical Sciences Graduate ProgramUniversity of California, San DiegoLa JollaUnited States
| | - Madison K Lehmer
- Department of Cellular and Molecular MedicineUniversity of California, San DiegoLa JollaUnited States
| | - Qiaozhen Ye
- Department of Cellular and Molecular MedicineUniversity of California, San DiegoLa JollaUnited States
| | - Götz Hagemann
- Gene Center and Department of BiochemistryLudwig-Maximilians-Universität MünchenMunichGermany
| | - Iracema Caballero
- Crystallographic MethodsInstitute of Molecular Biology of Barcelona (IBMB-CSIC)BarcelonaSpain
| | - Isabel Usón
- Crystallographic MethodsInstitute of Molecular Biology of Barcelona (IBMB-CSIC)BarcelonaSpain
- Institució Catalana de Recerca i Estudis Avançats (ICREA)BarcelonaSpain
| | - Amy J MacQueen
- Department of Molecular Biology and BiochemistryWesleyan UniversityMiddletownUnited States
| | - Franz Herzog
- Gene Center and Department of BiochemistryLudwig-Maximilians-Universität MünchenMunichGermany
| | - Kevin D Corbett
- Department of Cellular and Molecular MedicineUniversity of California, San DiegoLa JollaUnited States
- Department of ChemistryUniversity of California, San DiegoLa JollaUnited States
- Ludwig Institute for Cancer ResearchLa JollaUnited States
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48
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Tian H, Billings T, Petkov PM. CXXC1 is not essential for normal DNA double-strand break formation and meiotic recombination in mouse. PLoS Genet 2018; 14:e1007657. [PMID: 30365547 PMCID: PMC6221362 DOI: 10.1371/journal.pgen.1007657] [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: 04/20/2018] [Revised: 11/07/2018] [Accepted: 08/24/2018] [Indexed: 12/28/2022] Open
Abstract
In most mammals, including mice and humans, meiotic recombination is determined by the meiosis specific histone methytransferase PRDM9, which binds to specific DNA sequences and trimethylates histone 3 at lysine-4 and lysine-36 at the adjacent nucleosomes. These actions ensure successful DNA double strand break formation and repair that occur on the proteinaceous structure forming the chromosome axis. The process of hotspot association with the axis after their activation by PRDM9 is poorly understood. Previously, we and others have identified CXXC1, an ortholog of S. cerevisiae Spp1 in mammals, as a PRDM9 interactor. In yeast, Spp1 is a histone methyl reader that links H3K4me3 sites with the recombination machinery, promoting DSB formation. Here, we investigated whether CXXC1 has a similar function in mouse meiosis. We created two Cxxc1 conditional knockout mouse models to deplete CXXC1 generally in germ cells, and before the onset of meiosis. Surprisingly, male knockout mice were fertile, and the loss of CXXC1 in spermatocytes had no effect on PRDM9 hotspot trimethylation, double strand break formation or repair. Our results demonstrate that CXXC1 is not an essential link between PRDM9-activated recombination hotspot sites and DSB machinery and that the hotspot recognition pathway in mouse is independent of CXXC1. Meiotic recombination increases genetic diversity by ensuring novel combination of alleles passing correctly to the next generation. In most mammals, the meiotic recombination sites are determined by histone methyltransferase PRDM9. These sites are proposed to become associated with the chromosome axis with the participation of additional proteins and undergo double strand breaks, which are repaired by homologous recombination. In budding yeast, Spp1 (ortholog of CXXC1) binds to methylated H3K4 and connects these sites with the chromosome axis promoting DSB formation. However, our data suggest that even though CXXC1 interacts with PRDM9 in male germ cells, it does not play a crucial role in mouse meiotic recombination. These results indicate that, unlike in yeast, a recombination initiation pathway that includes CXXC1 could only serve as a non-essential pathway in mouse meiosis.
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Affiliation(s)
- Hui Tian
- The Jackson Laboratory, Bar Harbor, ME 04609, United States of America
| | - Timothy Billings
- The Jackson Laboratory, Bar Harbor, ME 04609, United States of America
| | - Petko M. Petkov
- The Jackson Laboratory, Bar Harbor, ME 04609, United States of America
- * E-mail:
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49
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Female Meiosis: Synapsis, Recombination, and Segregation in Drosophila melanogaster. Genetics 2018; 208:875-908. [PMID: 29487146 PMCID: PMC5844340 DOI: 10.1534/genetics.117.300081] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 10/18/2017] [Indexed: 12/11/2022] Open
Abstract
A century of genetic studies of the meiotic process in Drosophila melanogaster females has been greatly augmented by both modern molecular biology and major advances in cytology. These approaches, and the findings they have allowed, are the subject of this review. Specifically, these efforts have revealed that meiotic pairing in Drosophila females is not an extension of somatic pairing, but rather occurs by a poorly understood process during premeiotic mitoses. This process of meiotic pairing requires the function of several components of the synaptonemal complex (SC). When fully assembled, the SC also plays a critical role in maintaining homolog synapsis and in facilitating the maturation of double-strand breaks (DSBs) into mature crossover (CO) events. Considerable progress has been made in elucidating not only the structure, function, and assembly of the SC, but also the proteins that facilitate the formation and repair of DSBs into both COs and noncrossovers (NCOs). The events that control the decision to mature a DSB as either a CO or an NCO, as well as determining which of the two CO pathways (class I or class II) might be employed, are also being characterized by genetic and genomic approaches. These advances allow a reconsideration of meiotic phenomena such as interference and the centromere effect, which were previously described only by genetic studies. In delineating the mechanisms by which the oocyte controls the number and position of COs, it becomes possible to understand the role of CO position in ensuring the proper orientation of homologs on the first meiotic spindle. Studies of bivalent orientation have occurred in the context of numerous investigations into the assembly, structure, and function of the first meiotic spindle. Additionally, studies have examined the mechanisms ensuring the segregation of chromosomes that have failed to undergo crossing over.
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50
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Combined expansion microscopy with structured illumination microscopy for analyzing protein complexes. Nat Protoc 2018; 13:1869-1895. [PMID: 30072723 DOI: 10.1038/s41596-018-0023-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 05/09/2018] [Indexed: 12/19/2022]
Abstract
Biologists have long been fascinated with the organization and function of intricate protein complexes. Therefore, techniques for precisely imaging protein complexes and the location of proteins within these complexes are critically important and often require multidisciplinary collaboration. A challenge in these explorations is the limited resolution of conventional light microscopy. However, a new microscopic technique has circumvented this resolution limit by making the biological sample larger, thus allowing for super-resolution of the enlarged structure. This 'expansion' is accomplished by embedding the sample in a hydrogel that, when exposed to water, uniformly expands. Here, we present a protocol that transforms thick expansion microscopy (ExM) hydrogels into sections that are physically expanded four times, creating samples that are compatible with the super-resolution technique structured illumination microscopy (SIM). This super-resolution ExM method (ExM-SIM) allows the analysis of the three-dimensional (3D) organization of multiprotein complexes at ~30-nm lateral (xy) resolution. This protocol details the steps necessary for analysis of protein localization using ExM-SIM, including antibody labeling, hydrogel preparation, protease digestion, post-digestion antibody labeling, hydrogel embedding with tissue-freezing medium (TFM), cryosectioning, expansion, image alignment, and particle averaging. We have used this approach for 3D mapping of in situ protein localization in the Drosophila synaptonemal complex (SC), but it can be readily adapted to study thick tissues such as brain and organs in various model systems. This procedure can be completed in 5 d.
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