201
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Fowler KR, Sasaki M, Milman N, Keeney S, Smith GR. Evolutionarily diverse determinants of meiotic DNA break and recombination landscapes across the genome. Genome Res 2014; 24:1650-64. [PMID: 25024163 PMCID: PMC4199369 DOI: 10.1101/gr.172122.114] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Fission yeast Rec12 (Spo11 homolog) initiates meiotic recombination by forming developmentally programmed DNA double-strand breaks (DSBs). DSB distributions influence patterns of heredity and genome evolution, but the basis of the highly nonrandom choice of Rec12 cleavage sites is poorly understood, largely because available maps are of relatively low resolution and sensitivity. Here, we determined DSBs genome-wide at near-nucleotide resolution by sequencing the oligonucleotides attached to Rec12 following DNA cleavage. The single oligonucleotide size class allowed us to deeply sample all break events. We find strong evidence across the genome for differential DSB repair accounting for crossover invariance (constant cM/kb in spite of DSB hotspots). Surprisingly, about half of all crossovers occur in regions where DSBs occur at low frequency and are widely dispersed in location from cell to cell. These previously undetected, low-level DSBs thus play an outsized and crucial role in meiosis. We further find that the influence of underlying nucleotide sequence and chromosomal architecture differs in multiple ways from that in budding yeast. DSBs are not strongly restricted to nucleosome-depleted regions, as they are in budding yeast, but are nevertheless spatially influenced by chromatin structure. Our analyses demonstrate that evolutionarily fluid factors contribute to crossover initiation and regulation.
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Affiliation(s)
- Kyle R Fowler
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Mariko Sasaki
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA; Weill Graduate School of Medical Sciences of Cornell University, New York, New York 10065, USA
| | - Neta Milman
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Scott Keeney
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA; Weill Graduate School of Medical Sciences of Cornell University, New York, New York 10065, USA; Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Gerald R Smith
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA;
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202
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Abstract
Holliday junctions (HJs) can be formed between sister chromatids or homologous chromosomes during the recombinational repair of DNA lesions. A variety of pathways act upon HJs to remove them from DNA, in events that are critical for appropriate chromosome segregation. Despite the identification and characterization of multiple enzymes involved in HJ processing, the cellular mechanisms that regulate and implement pathway usage have only just started to be delineated. A conserved network of core cell-cycle kinases and phosphatases modulate HJ metabolism by exerting spatial and temporal control over the activities of two structure-selective nucleases: yeast Mus81-Mms4 (human MUS81-EME1) and Yen1 (human GEN1). These regulatory cycles operate to establish the sequential activation of HJ processing enzymes, implementing a hierarchy in pathway usage that ensure the elimination of chromosomal interactions which would otherwise interfere with chromosome segregation. Mus81-Mms4/EME1 and Yen1/GEN1 emerge to define a special class of enzymes, evolved to satisfy the cellular need of safeguarding the completion of DNA repair when on the verge of chromosome segregation.
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Affiliation(s)
- Joao Matos
- London Research Institute, Cancer Research UK, Clare Hall Laboratories, South Mimms, Herts EN6 3LD, UK
| | - Stephen C West
- London Research Institute, Cancer Research UK, Clare Hall Laboratories, South Mimms, Herts EN6 3LD, UK.
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203
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Che L, Wang K, Tang D, Liu Q, Chen X, Li Y, Hu Q, Shen Y, Yu H, Gu M, Cheng Z. OsHUS1 facilitates accurate meiotic recombination in rice. PLoS Genet 2014; 10:e1004405. [PMID: 24901798 PMCID: PMC4046934 DOI: 10.1371/journal.pgen.1004405] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 04/15/2014] [Indexed: 11/18/2022] Open
Abstract
Meiotic recombination normally takes place between allelic sequences on homologs. This process can also occur between non-allelic homologous sequences. Such ectopic interaction events can lead to chromosome rearrangements and are normally avoided. However, much remains unknown about how these ectopic interaction events are sensed and eliminated. In this study, using a screen in rice, we characterized a homolog of HUS1 and explored its function in meiotic recombination. In Oshus1 mutants, in conjunction with nearly normal homologous pairing and synapsis, vigorous, aberrant ectopic interactions occurred between nonhomologous chromosomes, leading to multivalent formation and subsequent chromosome fragmentation. These ectopic interactions relied on programed meiotic double strand breaks and were formed in a manner independent of the OsMER3-mediated interference-sensitive crossover pathway. Although early homologous recombination events occurred normally, the number of interference-sensitive crossovers was reduced in the absence of OsHUS1. Together, our results indicate that OsHUS1 might be involved in regulating ectopic interactions during meiosis, probably by forming the canonical RAD9-RAD1-HUS1 (9-1-1) complex. Meiosis is a special type of cell division that generates gametes for sexual reproduction. During meiosis, recombination not only occurs between allelic sequences on homologs, but also between non-allelic homologous sequences at dispersed loci. Such ectopic recombination is the main cause of chromosomal alterations and accounts for numerous genomic disorders in humans. To ensure genomic integrity, those ectopic recombinations must be quickly resolved. Despite the importance of ectopic recombination suppression, the mechanism underlying this process still remains largely unknown. Here, using rice as a model system, we identified the rice HUS1 homolog, a member of the RAD9-RAD1-HUS1 (9-1-1) complex, and elucidated its roles in meiotic recombination. In Oshus1, vigorous ectopic interactions occur between nonhomologous chromosomes, and the number of crossovers is reduced. We suspect that OsHUS1 participates in regulating ectopic interactions during meiosis, probably by forming the canonical RAD9-RAD1-HUS1 (9-1-1) complex.
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Affiliation(s)
- Lixiao Che
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Kejian Wang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Ding Tang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Qiaoquan Liu
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou, China
| | - Xiaojun Chen
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yafei Li
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Qing Hu
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yi Shen
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Hengxiu Yu
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou, China
| | - Minghong Gu
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou, China
| | - Zhukuan Cheng
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
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204
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Fukuda T, Fukuda N, Agostinho A, Hernández-Hernández A, Kouznetsova A, Höög C. STAG3-mediated stabilization of REC8 cohesin complexes promotes chromosome synapsis during meiosis. EMBO J 2014; 33:1243-55. [PMID: 24797475 PMCID: PMC4198027 DOI: 10.1002/embj.201387329] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 03/26/2014] [Accepted: 03/28/2014] [Indexed: 11/10/2022] Open
Abstract
Cohesion between sister chromatids in mitotic and meiotic cells is promoted by a ring-shaped protein structure, the cohesin complex. The cohesin core complex is composed of four subunits, including two structural maintenance of chromosome (SMC) proteins, one α-kleisin protein, and one SA protein. Meiotic cells express both mitotic and meiosis-specific cohesin core subunits, generating cohesin complexes with different subunit composition and possibly separate meiotic functions. Here, we have analyzed the in vivo function of STAG3, a vertebrate meiosis-specific SA protein. Mice with a hypomorphic allele of Stag3, which display a severely reduced level of STAG3, are viable but infertile. We show that meiocytes in homozygous mutant Stag3 mice display chromosome axis compaction, aberrant synapsis, impaired recombination and developmental arrest. We find that the three different α-kleisins present in meiotic cells show different dosage-dependent requirements for STAG3 and that STAG3-REC8 cohesin complexes have a critical role in supporting meiotic chromosome structure and functions.
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Affiliation(s)
- Tomoyuki Fukuda
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Nanaho Fukuda
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Ana Agostinho
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | | | - Anna Kouznetsova
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Christer Höög
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
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205
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Dot1-dependent histone H3K79 methylation promotes the formation of meiotic double-strand breaks in the absence of histone H3K4 methylation in budding yeast. PLoS One 2014; 9:e96648. [PMID: 24797370 PMCID: PMC4010517 DOI: 10.1371/journal.pone.0096648] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 04/09/2014] [Indexed: 11/19/2022] Open
Abstract
Epigenetic marks such as histone modifications play roles in various chromosome dynamics in mitosis and meiosis. Methylation of histones H3 at positions K4 and K79 is involved in the initiation of recombination and the recombination checkpoint, respectively, during meiosis in the budding yeast. Set1 promotes H3K4 methylation while Dot1 promotes H3K79 methylation. In this study, we carried out detailed analyses of meiosis in mutants of the SET1 and DOT1 genes as well as methylation-defective mutants of histone H3. We confirmed the role of Set1-dependent H3K4 methylation in the formation of double-strand breaks (DSBs) in meiosis for the initiation of meiotic recombination, and we showed the involvement of Dot1 (H3K79 methylation) in DSB formation in the absence of Set1-dependent H3K4 methylation. In addition, we showed that the histone H3K4 methylation-defective mutants are defective in SC elongation, although they seem to have moderate reduction of DSBs. This suggests that high levels of DSBs mediated by histone H3K4 methylation promote SC elongation.
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206
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Moktan H, Guiraldelli MF, Eyster CA, Zhao W, Lee CY, Mather T, Camerini-Otero RD, Sung P, Zhou DH, Pezza RJ. Solution structure and DNA-binding properties of the winged helix domain of the meiotic recombination HOP2 protein. J Biol Chem 2014; 289:14682-91. [PMID: 24711446 DOI: 10.1074/jbc.m114.548180] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The HOP2 protein is required for efficient double-strand break repair which ensures the proper synapsis of homologous chromosomes and normal meiotic progression. We previously showed that in vitro HOP2 shows two distinctive activities: when it is incorporated into a HOP2-MND1 heterodimer, it stimulates DMC1 and RAD51 recombination activities, and the purified HOP2 alone is proficient in promoting strand invasion. The structural and biochemical basis of HOP2 action in recombination are poorly understood; therefore, they are the focus of this work. Herein, we present the solution structure of the amino-terminal portion of mouse HOP2, which contains a typical winged helix DNA-binding domain. Together with NMR spectral changes in the presence of double-stranded DNA, protein docking on DNA, and mutation analysis to identify the amino acids involved in DNA coordination, our results on the three-dimensional structure of HOP2 provide key information on the fundamental structural and biochemical requirements directing the interaction of HOP2 with DNA. These results, in combination with mutational experiments showing the role of a coiled-coil structural feature involved in HOP2 self-association, allow us to explain important aspects of the function of HOP2 in recombination.
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Affiliation(s)
- Hem Moktan
- From the Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078
| | - Michel F Guiraldelli
- the Cell Cycle and Cancer Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Craig A Eyster
- the Cell Cycle and Cancer Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Weixing Zhao
- the Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Chih-Ying Lee
- the Cell Cycle and Cancer Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Timothy Mather
- the Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, the Department of Biochemistry and Molecular Biology, Oklahoma University Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - R Daniel Camerini-Otero
- the Genetics and Biochemistry Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Patrick Sung
- the Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Donghua H Zhou
- From the Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078
| | - Roberto J Pezza
- the Cell Cycle and Cancer Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, the Department of Cell Biology, Oklahoma University Health Science Center, Oklahoma City, Oklahoma 73126
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207
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Mehta GD, Agarwal M, Ghosh SK. Functional characterization of kinetochore protein, Ctf19 in meiosis I: an implication of differential impact of Ctf19 on the assembly of mitotic and meiotic kinetochores in Saccharomyces cerevisiae. Mol Microbiol 2014; 91:1179-99. [PMID: 24446862 DOI: 10.1111/mmi.12527] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2014] [Indexed: 11/29/2022]
Abstract
Meiosis is a specialized cell division process through which chromosome numbers are reduced by half for the generation of gametes. Kinetochore, a multiprotein complex that connects centromeres to microtubules, plays essential role in chromosome segregation. Ctf19 is the key central kinetochore protein that recruits all the other non-essential proteins of the Ctf19 complex in budding yeast. Earlier studies have shown the role of Ctf19 complex in enrichment of cohesin around the centromeres both during mitosis and meiosis, leading to sister chromatid cohesion and meiosis II disjunction. Here we show that Ctf19 is also essential for the proper execution of the meiosis I specific unique events, such as non-homologous centromere coupling, homologue pairing, chiasmata resolution and proper orientation of homologues and sister chromatids with respect to the spindle poles. Additionally, this investigation reveals that proper kinetochore function is required for faithful chromosome condensation in meiosis. Finally, this study suggests that absence of Ctf19 affects the integrity of meiotic kinetochore differently than that of the mitotic kinetochore. Consequently, absence of Ctf19 leads to gross chromosome missegregation during meiosis as compared with mitosis. Hence, this study reports for the first time the differential impact of a non-essential kinetochore protein on the mitotic and meiotic kinetochore ensembles and hence chromosome segregation.
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Affiliation(s)
- Gunjan D Mehta
- Department of Biosciences and Bioengineering, Wadhawani Research Centre of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai, 40076, India
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208
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Mailhes JB, Marchetti F. Advances in understanding the genetic causes and mechanisms of female germ cell aneuploidy. ACTA ACUST UNITED AC 2014. [DOI: 10.1586/eog.10.62] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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209
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Synchronized fission yeast meiosis using an ATP analog-sensitive Pat1 protein kinase. Nat Protoc 2014; 9:223-31. [PMID: 24385151 DOI: 10.1038/nprot.2014.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Synchronous cultures are often indispensable for studying meiosis. Here we present an optimized protocol for induction of synchronous meiosis in the fission yeast Schizosaccharomyces pombe. Chemical inactivation of an ATP analog-sensitive form of the Pat1 kinase (pat1-as2) by adding the ATP analog 1-NM-PP1 in G1-arrested cells allows the induction of synchronous meiosis at optimal temperature (25°C). Importantly, this protocol eliminates detrimental effects of elevated temperature (34°C), which is required to inactivate the commonly used temperature-sensitive Pat1 kinase mutant (pat1-114). The addition of the mat-Pc gene to a mat1-M strain further improves chromosome segregation and spore viability. Thus, our protocol offers highly synchronous meiosis at optimal temperature, with most characteristics similar to those of wild-type meiosis. The synchronization protocol can be completed in 5 d (not including strain production, which may take as long as 2 or 3 months).
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210
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Kobayashi W, Sekine S, Machida S, Kurumizaka H. Green fluorescent protein fused to the C terminus of RAD51 specifically interferes with secondary DNA binding by the RAD51-ssDNA complex. Genes Genet Syst 2014; 89:169-79. [DOI: 10.1266/ggs.89.169] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Wataru Kobayashi
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University
| | - Satoshi Sekine
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University
| | - Shinichi Machida
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University
| | - Hitoshi Kurumizaka
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University
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211
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Liu Y, Gaines WA, Callender T, Busygina V, Oke A, Sung P, Fung JC, Hollingsworth NM. Down-regulation of Rad51 activity during meiosis in yeast prevents competition with Dmc1 for repair of double-strand breaks. PLoS Genet 2014; 10:e1004005. [PMID: 24465215 PMCID: PMC3900393 DOI: 10.1371/journal.pgen.1004005] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 10/22/2013] [Indexed: 11/18/2022] Open
Abstract
Interhomolog recombination plays a critical role in promoting proper meiotic chromosome segregation but a mechanistic understanding of this process is far from complete. In vegetative cells, Rad51 is a highly conserved recombinase that exhibits a preference for repairing double strand breaks (DSBs) using sister chromatids, in contrast to the conserved, meiosis-specific recombinase, Dmc1, which preferentially repairs programmed DSBs using homologs. Despite the different preferences for repair templates, both Rad51 and Dmc1 are required for interhomolog recombination during meiosis. This paradox has recently been explained by the finding that Rad51 protein, but not its strand exchange activity, promotes Dmc1 function in budding yeast. Rad51 activity is inhibited in dmc1Δ mutants, where the failure to repair meiotic DSBs triggers the meiotic recombination checkpoint, resulting in prophase arrest. The question remains whether inhibition of Rad51 activity is important during wild-type meiosis, or whether inactivation of Rad51 occurs only as a result of the absence of DMC1 or checkpoint activation. This work shows that strains in which mechanisms that down-regulate Rad51 activity are removed exhibit reduced numbers of interhomolog crossovers and noncrossovers. A hypomorphic mutant, dmc1-T159A, makes less stable presynaptic filaments but is still able to mediate strand exchange and interact with accessory factors. Combining dmc1-T159A with up-regulated Rad51 activity reduces interhomolog recombination and spore viability, while increasing intersister joint molecule formation. These results support the idea that down-regulation of Rad51 activity is important during meiosis to prevent Rad51 from competing with Dmc1 for repair of meiotic DSBs.
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Affiliation(s)
- Yan Liu
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - William A. Gaines
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Tracy Callender
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Valeria Busygina
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Ashwini Oke
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, California, United States of America
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jennifer C. Fung
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, California, United States of America
| | - Nancy M. Hollingsworth
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
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212
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Pezza RJ, Voloshin ON, Volodin AA, Boateng KA, Bellani MA, Mazin AV, Camerini-Otero RD. The dual role of HOP2 in mammalian meiotic homologous recombination. Nucleic Acids Res 2013; 42:2346-57. [PMID: 24304900 PMCID: PMC3936763 DOI: 10.1093/nar/gkt1234] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Deletion of Hop2 in mice eliminates homologous chromosome synapsis and disrupts double-strand break (DSB) repair through homologous recombination. HOP2 in vitro shows two distinctive activities: when it is incorporated into a HOP2–MND1 complex it stimulates DMC1 and RAD51 recombination activities and the purified HOP2 alone is proficient in promoting strand invasion. We observed that a fraction of Mnd1−/− spermatocytes, which express HOP2 but apparently have inactive DMC1 and RAD51 due to lack of the HOP2–MND1 complex, exhibits a high level of chromosome synapsis and that most DSBs in these spermatocytes are repaired. This suggests that DSB repair catalyzed solely by HOP2 supports homologous chromosome pairing and synapsis. In addition, we show that in vitro HOP2 promotes the co-aggregation of ssDNA with duplex DNA, binds to ssDNA leading to unstacking of the bases, and promotes the formation of a three-strand synaptic intermediate. However, HOP2 shows distinctive mechanistic signatures as a recombinase. Namely, HOP2-mediated strand exchange does not require ATP and, in contrast to DMC1, joint molecules formed by HOP2 are more sensitive to mismatches and are efficiently dissociated by RAD54. We propose that HOP2 may act as a recombinase with specific functions in meiosis.
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Affiliation(s)
- Roberto J Pezza
- Oklahoma Medical Research Foundation, Oklahoma City, 73104 OK, USA, Department of Cell Biology, Oklahoma University Health Science Center, Oklahoma City, 73126 OK, USA, Genetics and Biochemistry Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, 20892 MD, USA, Institute of Molecular Genetics of the Russian Academy of Sciences, 123182 Moscow, Russia, Biomedical Research Center, National Institute of Aging, Baltimore, 21224 MA, USA and Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, 19102 PA, USA
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213
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CDK-dependent nuclear localization of B-cyclin Clb1 promotes FEAR activation during meiosis I in budding yeast. PLoS One 2013; 8:e79001. [PMID: 24223874 PMCID: PMC3815228 DOI: 10.1371/journal.pone.0079001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 09/25/2013] [Indexed: 11/19/2022] Open
Abstract
Cyclin-dependent kinases (CDK) are master regulators of the cell cycle in eukaryotes. CDK activity is regulated by the presence, post-translational modification and spatial localization of its regulatory subunit cyclin. In budding yeast, the B-cyclin Clb1 is phosphorylated and localizes to the nucleus during meiosis I. However the functional significance of Clb1's phosphorylation and nuclear localization and their mutual dependency is unknown. In this paper, we demonstrate that meiosis-specific phosphorylation of Clb1 requires its import to the nucleus but not vice versa. While Clb1 phosphorylation is dependent on activity of both CDK and polo-like kinase Cdc5, its nuclear localization requires CDK but not Cdc5 activity. Furthermore we show that increased nuclear localization of Clb1 during meiosis enhances activation of FEAR (Cdc Fourteen Early Anaphase Release) pathway. We discuss the significance of our results in relation to regulation of exit from meiosis I.
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214
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Polakova S, Benko Z, Zhang L, Gregan J. Mal3, the Schizosaccharomyces pombe homolog of EB1, is required for karyogamy and for promoting oscillatory nuclear movement during meiosis. Cell Cycle 2013; 13:72-7. [PMID: 24196444 PMCID: PMC3925738 DOI: 10.4161/cc.26815] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Two successive rounds of chromosome segregation following a single round of DNA replication enable the production of haploid gametes during meiosis. In the fission yeast Schizosaccharomyces pombe, karyogamy is the process where the nuclei from 2 haploid cells fuse to create a diploid nucleus, which then undergoes meiosis to produce 4 haploid spores. By screening a collection of S. pombe deletion strains, we found that the deletion of 2 genes, mal3 and mto1, leads to the production of asci containing up to 8 spores. Here, we show that Mal3, the fission yeast member of the EB1 family of conserved microtubule plus-end tracking proteins, is required for karyogamy, oscillatory nuclear movement, and proper segregation of chromosomes during meiosis. In the absence of Mal3, meiosis frequently initiates before the completion of karyogamy, thus producing up to 8 nuclei in a single ascus. Our results provide new evidence that fission yeast can initiate meiosis prior to completing karyogamy.
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Affiliation(s)
- Silvia Polakova
- Max F. Perutz Laboratories; Department of Chromosome Biology; University of Vienna; Vienna, Austria
| | - Zsigmond Benko
- Max F. Perutz Laboratories; Department of Chromosome Biology; University of Vienna; Vienna, Austria
| | - Lijuan Zhang
- Max F. Perutz Laboratories; Department of Chromosome Biology; University of Vienna; Vienna, Austria
| | - Juraj Gregan
- Max F. Perutz Laboratories; Department of Chromosome Biology; University of Vienna; Vienna, Austria; Department of Genetics; Comenius University; Bratislava, Slovak Republic
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215
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Morozumi Y, Ino R, Ikawa S, Mimida N, Shimizu T, Toki S, Ichikawa H, Shibata T, Kurumizaka H. Homologous pairing activities of two rice RAD51 proteins, RAD51A1 and RAD51A2. PLoS One 2013; 8:e75451. [PMID: 24124491 PMCID: PMC3790826 DOI: 10.1371/journal.pone.0075451] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 08/15/2013] [Indexed: 12/24/2022] Open
Abstract
In higher eukaryotes, RAD51 functions as an essential protein in homologous recombination and recombinational repair of DNA double strand breaks. During these processes, RAD51 catalyzes homologous pairing between single-stranded DNA and double-stranded DNA. Japonica cultivars of rice (Oryza sativa) encode two RAD51 proteins, RAD51A1 and RAD51A2, whereas only one RAD51 exists in yeast and mammals. However, the functional differences between RAD51A1 and RAD51A2 have not been elucidated, because their biochemical properties have not been characterized. In the present study, we purified RAD51A1 and RAD51A2, and found that RAD51A2 robustly promotes homologous pairing in vitro. RAD51A1 also possesses homologous-pairing activity, but it is only about 10% of the RAD51A2 activity. Both RAD51A1 and RAD51A2 bind to ssDNA and dsDNA, and their DNA binding strictly requires ATP, which modulates the polymer formation activities of RAD51A1 and RAD51A2. These findings suggest that although both RAD51A1 and RAD51A2 have the potential to catalyze homologous pairing, RAD51A2 may be the major recombinase in rice.
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Affiliation(s)
- Yuichi Morozumi
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo, Japan
| | - Ryohei Ino
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo, Japan
| | | | - Naozumi Mimida
- National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | - Takeshi Shimizu
- National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | - Seiichi Toki
- National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | - Hiroaki Ichikawa
- National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | | | - Hitoshi Kurumizaka
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo, Japan
- * E-mail:
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216
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Duan W, Liu C, Wu H, Chen C, Zhang T, Gao P, Luo X, Yu Z, Zhou Z. Effects of exposure to extremely low frequency magnetic fields on spermatogenesis in adult rats. Bioelectromagnetics 2013; 35:58-69. [PMID: 24122970 DOI: 10.1002/bem.21816] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 08/18/2013] [Indexed: 12/17/2022]
Abstract
The constant exposure of modern society to extremely low frequency magnetic fields (ELF-MF) has raised considerable concerns about the potential risks to male reproduction. However, the epidemiological and experimental data remain contradictory and inconclusive. In the present study, we investigated the effects of 50 Hz ELF-MF of 500 µT applied 4 h/day, 7 days/week for 4 and 8 weeks on male reproduction, focusing on changes in spermatogenesis. Several biological endpoints related to testicular function and spermatogenesis were measured, including the following: body mass, masses of testes and epididymis, sperm count and abnormal sperm ratio in the caudal epididymis, serum testosterone level, testicular histology, frequency of 14 stages of the cycle of the seminiferous epithelium and of four stages of meiosis I, germ cell apoptosis and testicular oxidative status. No significant differences were found in the biological endpoints between the sham control and the exposed rats in either the 4- or 8-week exposure period. These negative results may result from the lack of change in serum testosterone. In conclusion, our study indicates that exposure to low intensity ELF-MF may have no adverse effects on spermatogenesis.
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Affiliation(s)
- Weixia Duan
- Department of Occupational Health, Third Military Medical University, Chongqing, People's Republic of China
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217
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Clément Y, Arndt PF. Meiotic recombination strongly influences GC-content evolution in short regions in the mouse genome. Mol Biol Evol 2013; 30:2612-8. [PMID: 24030552 DOI: 10.1093/molbev/mst154] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Meiotic recombination is known to influence GC-content evolution in large regions of mammalian genomes by favoring the fixation of G and C alleles and increasing the rate of A/T to G/C substitutions. This process is known as GC-biased gene conversion (gBGC). Until recently, genome-wide measures of fine-scale recombination activity were unavailable in mice. Additionally, comparative studies focusing on mouse were limited as the closest organism with its genome fully sequenced was rat. Here, we make use of the recent mapping of double strand breaks (DSBs), the first step of meiotic recombination, in the mouse genome and of the sequencing of mouse closely related subspecies to analyze the fine-scale evolutionary signature of meiotic recombination on GC-content evolution in recombination hotspots, short regions that undergo extreme rates of recombination. We measure substitution rates around DSB hotspots and observe that gBGC is affecting a very short region (≈ 1 kbp) in length around these hotspots. Furthermore, we can infer that the locations of hotspots evolved rapidly during mouse evolution.
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Affiliation(s)
- Yves Clément
- Montpellier SupAgro, Unité Mixte de Recherche 1334, Amélioration Génétique et Adaptation des Plantes Méditerranéennes et Tropicales, Montpellier, France
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218
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Yin FX, Li GP, Bai CL, Liu Y, Wei ZY, Liang CG, Bunch TD, Zan LS. SGO1 maintains bovine meiotic and mitotic centromeric cohesions of sister chromatids and directly affects embryo development. PLoS One 2013; 8:e73636. [PMID: 24019931 PMCID: PMC3760824 DOI: 10.1371/journal.pone.0073636] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 07/19/2013] [Indexed: 12/19/2022] Open
Abstract
Shugoshin (SGO) is a critical factor that enforces cohesion from segregation of paired sister chromatids during mitosis and meiosis. It has been studied mainly in invertebrates. Knowledge of SGO(s) in a mammalian system has only been reported in the mouse and Hela cells. In this study, the functions of SGO1 in bovine oocytes during meiotic maturation, early embryonic development and somatic cell mitosis were investigated. The results showed that SGO1 was expressed from germinal vesicle (GV) to the metaphase II stage. SGO1 accumulated on condensed and scattered chromosomes from pre-metaphase I to metaphase II. The over-expression of SGO1 did not interfere with the process of homologous chromosome separation, although once separated they were unable to move to the opposing spindle poles. This often resulted in the formation of oocytes with 60 replicated chromosomes. Depletion of SGO1 in GV oocytes affected chromosomal separation resulting in abnormal chromosome alignment at a significantly higher proportion than in control oocytes. Knockdown of SGO1 expression significantly decreased the embryonic developmental rate and quality. To further confirm the function(s) of SGO1 during mitosis, bovine embryonic fibroblast cells were transfected with SGO1 siRNAs. SGO1 depletion induced the premature dissociation of chromosomal cohesion at the centromere and along the chromosome arm giving rise to abnormal appearing mitotic patterns. The results of this study infer that SGO1 is involved in the centromeric cohesion of sister chromatids and chromosomal movement towards the spindle poles. Depletion of SGO1 causes arrestment of cell division in meiosis and mitosis.
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Affiliation(s)
- Feng-Xia Yin
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, China
| | - Guang-Peng Li
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, China
- * E-mail:
| | - Chun-Ling Bai
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, China
| | - Yang Liu
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Zhu-Ying Wei
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, China
| | - Cheng-Guang Liang
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, China
| | - Thomas D. Bunch
- Department of Animal, Dairy and Veterinary Sciences, Utah State University, Logan, Utah, United States of America
| | - Lin-Sen Zan
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
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219
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Kuleszewicz K, Fu X, Kudo NR. Cohesin loading factor Nipbl localizes to chromosome axes during mammalian meiotic prophase. Cell Div 2013; 8:12. [PMID: 23967866 PMCID: PMC3765518 DOI: 10.1186/1747-1028-8-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 08/12/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sister chromatid cohesion mediated by the cohesin complex is essential for accurate chromosome segregation during mitosis and meiosis. Loading of cohesin onto chromosomes is dependent on another protein complex called kollerin, containing Nipbl/Scc2 and Mau2/Scc4. Nipbl is an evolutionarily conserved large protein whose haploinsufficiency in humans causes a developmental disorder called Cornelia de Lange syndrome. Although the function of Nipbl homologues for chromosome cohesion in meiotic cells of non-vertebrate models has been elucidated, Nipbl has not been characterized so far in mammalian spermatocytes or oocytes. FINDINGS Here we describe our analyses on the expression and localization of Nipbl in nuclei of mouse spermatocytes and oocytes at different stages of meiotic prophase. In both spermatocytes and oocytes we found that Nipbl is associated with the axial/lateral element of the synaptonemal complex (AE/LE) to which cohesin also localizes. Interestingly, Nipbl in spermatocytes, but not in oocytes, dissociates from the AE/LE at mid-pachytene stage coincident with completion of DNA double-strand break repair. CONCLUSIONS Our data propose that cohesin loading activity is maintained during early stages of meiotic prophase in mammalian spermatocytes and oocytes.
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Affiliation(s)
- Katarzyna Kuleszewicz
- IRDB, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital, London W12 0NN, UK.
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220
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Stamper EL, Rodenbusch SE, Rosu S, Ahringer J, Villeneuve AM, Dernburg AF. Identification of DSB-1, a protein required for initiation of meiotic recombination in Caenorhabditis elegans, illuminates a crossover assurance checkpoint. PLoS Genet 2013; 9:e1003679. [PMID: 23990794 PMCID: PMC3749324 DOI: 10.1371/journal.pgen.1003679] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 06/14/2013] [Indexed: 12/11/2022] Open
Abstract
Meiotic recombination, an essential aspect of sexual reproduction, is initiated by programmed DNA double-strand breaks (DSBs). DSBs are catalyzed by the widely-conserved Spo11 enzyme; however, the activity of Spo11 is regulated by additional factors that are poorly conserved through evolution. To expand our understanding of meiotic regulation, we have characterized a novel gene, dsb-1, that is specifically required for meiotic DSB formation in the nematode Caenorhabditis elegans. DSB-1 localizes to chromosomes during early meiotic prophase, coincident with the timing of DSB formation. DSB-1 also promotes normal protein levels and chromosome localization of DSB-2, a paralogous protein that plays a related role in initiating recombination. Mutations that disrupt crossover formation result in prolonged DSB-1 association with chromosomes, suggesting that nuclei may remain in a DSB-permissive state. Extended DSB-1 localization is seen even in mutants with defects in early recombination steps, including spo-11, suggesting that the absence of crossover precursors triggers the extension. Strikingly, failure to form a crossover precursor on a single chromosome pair is sufficient to extend the localization of DSB-1 on all chromosomes in the same nucleus. Based on these observations we propose a model for crossover assurance that acts through DSB-1 to maintain a DSB-permissive state until all chromosome pairs acquire crossover precursors. This work identifies a novel component of the DSB machinery in C. elegans, and sheds light on an important pathway that regulates DSB formation for crossover assurance. For most eukaryotes, recombination between homologous chromosomes during meiosis is an essential aspect of sexual reproduction. Meiotic recombination is initiated by programmed double-strand breaks in DNA, which have the potential to induce mutations if not efficiently repaired. To better understand the mechanisms that govern the initiation of recombination and regulate the formation of double-strand breaks, we use the nematode Caenorhabditis elegans as a model system. Here we describe a new gene, dsb-1, that is required for double-strand break formation in C. elegans. Through analysis of the encoded DSB-1 protein we illuminate an important regulatory pathway that promotes crossover recombination events on all chromosome pairs to ensure successful meiosis.
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Affiliation(s)
- Ericca L. Stamper
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences (QB3), University of California, Berkeley; Berkeley, California, United States of America
| | - Stacia E. Rodenbusch
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences (QB3), University of California, Berkeley; Berkeley, California, United States of America
| | - Simona Rosu
- Department of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Julie Ahringer
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Anne M. Villeneuve
- Department of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Abby F. Dernburg
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences (QB3), University of California, Berkeley; Berkeley, California, United States of America
- Department of Genome Dynamics, Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
- * E-mail:
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221
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Eto K, Shiotsuki M, Abe SI. Nociceptin induces Rec8 phosphorylation and meiosis in postnatal murine testes. Endocrinology 2013; 154:2891-9. [PMID: 23720425 DOI: 10.1210/en.2012-1977] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phosphorylated Rec8, a key component of cohesin, mediates the association and disassociation, "dynamics," of chromosomes occurring in synaptonemal complex formation, crossover recombination, and sister chromatid cohesion during meiosis. Yet, the extrinsic factors triggering meiotic chromosome dynamics remain elusive. We have recently found that nociceptin, known as a neuropeptide, is up-regulated by follicle-stimulating hormone in Sertoli cells in postnatal murine testes; however, very little is known about the functional role of nociceptin in spermatogenesis. Here, we show that nociceptin induces Rec8 phosphorylation, triggering chromosome dynamics, in spermatocytes during meiosis in postnatal murine testes. The nociceptin receptor Oprl-1 is exclusively expressed in the plasma membrane of testicular germ cells, mostly spermatocytes. Treatment of testes with nociceptin resulted in a rapid phosphorylation of Rec8. Injection of nociceptin into mice stimulated Rec8 phosphorylation and meiotic chromosome dynamics in testes, whereas injection of nocistatin, a specific inhibitor of nociceptin, abolished them. These findings suggest that nociceptin is a novel extrinsic factor that plays a crucial role in the progress of meiosis.
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Affiliation(s)
- Ko Eto
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kurokami, Chuo-ku, Kumamoto 860-8555, Japan.
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222
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Verver DE, van Pelt AMM, Repping S, Hamer G. Role for rodent Smc6 in pericentromeric heterochromatin domains during spermatogonial differentiation and meiosis. Cell Death Dis 2013; 4:e749. [PMID: 23907463 PMCID: PMC3763431 DOI: 10.1038/cddis.2013.269] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/14/2013] [Accepted: 06/19/2013] [Indexed: 01/08/2023]
Abstract
Chromatin structure and function are for a large part determined by the six members of the structural maintenance of chromosomes (SMC) protein family, which form three heterodimeric complexes: Smc1/3 (cohesin), Smc2/4 (condensin) and Smc5/6. Each complex has distinct and important roles in chromatin dynamics, gene expression and differentiation. In yeast and Drosophila, Smc6 is involved in recombinational repair, restarting collapsed replication forks and prevention of recombination in repetitive sequences such as rDNA and pericentromeric heterochromatin. Although such DNA damage control mechanisms, as well as highly dynamic changes in chromatin composition and function, are essential for gametogenesis, knowledge on Smc6 function in mammalian systems is limited. We therefore have investigated the role of Smc6 during mammalian spermatogonial differentiation, meiosis and subsequent spermiogenesis. We found that, during mouse spermatogenesis, Smc6 functions as part of meiotic pericentromeric heterochromatin domains that are initiated when differentiating spermatogonia become irreversibly committed toward meiosis. To our knowledge, we are the first to provide insight into how commitment toward meiosis alters chromatin structure and dynamics, thereby setting apart differentiating spermatogonia from the undifferentiated spermatogonia, including the spermatogonial stem cells. Interestingly, Smc6 is not essential for spermatogonial mitosis, whereas Smc6-negative meiotic cells appear unable to finish their first meiotic division. Importantly, during meiosis, we find that DNA repair or recombination sites, marked by γH2AX or Rad51 respectively, do not co-localize with the pericentromeric heterochromatin domains where Smc6 is located. Considering the repetitive nature of these domains and that Smc6 has been previously shown to prevent recombination in repetitive sequences, we hypothesize that Smc6 has a role in the prevention of aberrant recombination events between pericentromeric regions during the first meiotic prophase that would otherwise cause chromosomal aberrations leading to apoptosis, meiotic arrest or aneuploidies.
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Affiliation(s)
- D E Verver
- Center for Reproductive Medicine, Women's and Children's Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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223
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Yan R, McKee BD. The cohesion protein SOLO associates with SMC1 and is required for synapsis, recombination, homolog bias and cohesion and pairing of centromeres in Drosophila Meiosis. PLoS Genet 2013; 9:e1003637. [PMID: 23874232 PMCID: PMC3715423 DOI: 10.1371/journal.pgen.1003637] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 06/01/2013] [Indexed: 11/29/2022] Open
Abstract
Cohesion between sister chromatids is mediated by cohesin and is essential for proper meiotic segregation of both sister chromatids and homologs. solo encodes a Drosophila meiosis-specific cohesion protein with no apparent sequence homology to cohesins that is required in male meiosis for centromere cohesion, proper orientation of sister centromeres and centromere enrichment of the cohesin subunit SMC1. In this study, we show that solo is involved in multiple aspects of meiosis in female Drosophila. Null mutations in solo caused the following phenotypes: 1) high frequencies of homolog and sister chromatid nondisjunction (NDJ) and sharply reduced frequencies of homolog exchange; 2) reduced transmission of a ring-X chromosome, an indicator of elevated frequencies of sister chromatid exchange (SCE); 3) premature loss of centromere pairing and cohesion during prophase I, as indicated by elevated foci counts of the centromere protein CID; 4) instability of the lateral elements (LE)s and central regions of synaptonemal complexes (SCs), as indicated by fragmented and spotty staining of the chromosome core/LE component SMC1 and the transverse filament protein C(3)G, respectively, at all stages of pachytene. SOLO and SMC1 are both enriched on centromeres throughout prophase I, co-align along the lateral elements of SCs and reciprocally co-immunoprecipitate from ovarian protein extracts. Our studies demonstrate that SOLO is closely associated with meiotic cohesin and required both for enrichment of cohesin on centromeres and stable assembly of cohesin into chromosome cores. These events underlie and are required for stable cohesion of centromeres, synapsis of homologous chromosomes, and a recombination mechanism that suppresses SCE to preferentially generate homolog crossovers (homolog bias). We propose that SOLO is a subunit of a specialized meiotic cohesin complex that mediates both centromeric and axial arm cohesion and promotes homolog bias as a component of chromosome cores. Sexual reproduction entails an intricate 2-step division called meiosis in which homologous chromosomes and sister chromatids are sequentially segregated to yield gametes (eggs and sperm) with exactly one copy of each chromosome. The Drosophila meiosis protein SOLO is essential for cohesion between sister chromatids. SOLO localizes to centromeres throughout meiosis where it collaborates with the conserved cohesin complex to enable sister centromeres to orient properly – to the same pole during the first division and to opposite poles during the second division. In solo mutants, sister chromatids become disconnected early in meiosis and segregate randomly through both meiotic divisions generating gametes with random (and mostly wrong) numbers of chromosomes. In this study we show that SOLO also localizes to chromosome arms where it is required to construct stable synaptonemal complexes that connect homologs while they recombine. In addition, SOLO is required to prevent crossovers between sister chromatids, as only homolog crossovers are useful for forming the interhomolog connections (chiasmata) needed for homolog segregation. SOLO collaborates with cohesin for these tasks as well. We propose that SOLO is a subunit of a specialized meiotic cohesin complex and a multi-purpose cohesion protein that regulates several meiotic processes needed for proper chromosome segregation.
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Affiliation(s)
- Rihui Yan
- Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
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224
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Sarkar S, Shenoy RT, Dalgaard JZ, Newnham L, Hoffmann E, Millar JBA, Arumugam P. Monopolin subunit Csm1 associates with MIND complex to establish monopolar attachment of sister kinetochores at meiosis I. PLoS Genet 2013; 9:e1003610. [PMID: 23861669 PMCID: PMC3701701 DOI: 10.1371/journal.pgen.1003610] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 05/20/2013] [Indexed: 01/21/2023] Open
Abstract
Sexually reproducing organisms halve their cellular ploidy during gametogenesis by undergoing a specialized form of cell division known as meiosis. During meiosis, a single round of DNA replication is followed by two rounds of nuclear divisions (referred to as meiosis I and II). While sister kinetochores bind to microtubules emanating from opposite spindle poles during mitosis, they bind to microtubules originating from the same spindle pole during meiosis I. This phenomenon is referred to as mono-orientation and is essential for setting up the reductional mode of chromosome segregation during meiosis I. In budding yeast, mono-orientation depends on a four component protein complex referred to as monopolin which consists of two nucleolar proteins Csm1 and Lrs4, meiosis-specific protein Mam1 of unknown function and casein kinase Hrr25. Monopolin complex binds to kinetochores during meiosis I and prevents bipolar attachments. Although monopolin associates with kinetochores during meiosis I, its binding site(s) on the kinetochore is not known and its mechanism of action has not been established. By carrying out an imaging-based screen we have found that the MIND complex, a component of the central kinetochore, is required for monopolin association with kinetochores during meiosis. Furthermore, we demonstrate that interaction of monopolin subunit Csm1 with the N-terminal domain of MIND complex subunit Dsn1, is essential for both the association of monopolin with kinetochores and for monopolar attachment of sister kinetochores during meiosis I. As such this provides the first functional evidence for a monopolin-binding site at the kinetochore.
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Affiliation(s)
| | | | | | - Louise Newnham
- MRC Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Eva Hoffmann
- MRC Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
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225
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Potential role of meiosis proteins in melanoma chromosomal instability. J Skin Cancer 2013; 2013:190109. [PMID: 23840955 PMCID: PMC3694528 DOI: 10.1155/2013/190109] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 05/21/2013] [Indexed: 12/05/2022] Open
Abstract
Melanomas demonstrate chromosomal instability (CIN). In fact, CIN can be used to differentiate melanoma from benign nevi. The exact molecular mechanisms that drive CIN in melanoma have yet to be fully elucidated. Cancer/testis antigens are a unique group of germ cell proteins that are found to be primarily expressed in melanoma as compared to benign nevi. The abnormal expression of these germ cell proteins, normally expected only in the testis and ovaries, in somatic cells may lead to interference with normal cellular pathways. Germ cell proteins that may be particularly critical in CIN are meiosis proteins. Here, we review pathways unique to meiosis with a focus on how the aberrant expression of meiosis proteins in normal mitotic cells “meiomitosis” could impact chromosomal instability in melanoma and other cancers.
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226
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Direct and indirect control of the initiation of meiotic recombination by DNA damage checkpoint mechanisms in budding yeast. PLoS One 2013; 8:e65875. [PMID: 23762445 PMCID: PMC3677890 DOI: 10.1371/journal.pone.0065875] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 04/29/2013] [Indexed: 12/27/2022] Open
Abstract
Meiotic recombination plays an essential role in the proper segregation of chromosomes at meiosis I in many sexually reproducing organisms. Meiotic recombination is initiated by the scheduled formation of genome-wide DNA double-strand breaks (DSBs). The timing of DSB formation is strictly controlled because unscheduled DSB formation is detrimental to genome integrity. Here, we investigated the role of DNA damage checkpoint mechanisms in the control of meiotic DSB formation using budding yeast. By using recombination defective mutants in which meiotic DSBs are not repaired, the effect of DNA damage checkpoint mutations on DSB formation was evaluated. The Tel1 (ATM) pathway mainly responds to unresected DSB ends, thus the sae2 mutant background in which DSB ends remain intact was employed. On the other hand, the Mec1 (ATR) pathway is primarily used when DSB ends are resected, thus the rad51 dmc1 double mutant background was employed in which highly resected DSBs accumulate. In order to separate the effect caused by unscheduled cell cycle progression, which is often associated with DNA damage checkpoint defects, we also employed the ndt80 mutation which permanently arrests the meiotic cell cycle at prophase I. In the absence of Tel1, DSB formation was reduced in larger chromosomes (IV, VII, II and XI) whereas no significant reduction was found in smaller chromosomes (III and VI). On the other hand, the absence of Rad17 (a critical component of the ATR pathway) lead to an increase in DSB formation (chromosomes VII and II were tested). We propose that, within prophase I, the Tel1 pathway facilitates DSB formation, especially in bigger chromosomes, while the Mec1 pathway negatively regulates DSB formation. We also identified prophase I exit, which is under the control of the DNA damage checkpoint machinery, to be a critical event associated with down-regulating meiotic DSB formation.
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227
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Wang L, Lu A, Zhou HX, Sun R, Zhao J, Zhou CJ, Shen JP, Wu SN, Liang CG. Casein kinase 1 alpha regulates chromosome congression and separation during mouse oocyte meiotic maturation and early embryo development. PLoS One 2013; 8:e63173. [PMID: 23690993 PMCID: PMC3655170 DOI: 10.1371/journal.pone.0063173] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 03/28/2013] [Indexed: 11/18/2022] Open
Abstract
Casein kinase I alpha (CK1α) is a member of serine/threonine protein kinase, generally present in all eukaryotes. In mammals, CK1α regulates the transition from interphase to metaphase in mitosis. However, little is known about its role in meiosis. Here we examined Ck1α mRNA and protein expression, as well as its subcellular localization in mouse oocytes from germinal vesicle to the late 1-cell stage. Our results showed that the expression level of CK1α was increased in metaphase. Immunostaining results showed that CK1α colocalized with condensed chromosomes during oocyte meiotic maturation and early embryo development. We used the loss-of-function approach by employing CK1α specific morpholino injection to block the function of CK1α. This functional blocking leads to failure of polar body 1 (PB1) extrusion, chromosome misalignment and MII plate incrassation. We further found that D4476, a specific and efficient CK1 inhibitor, decreased the rate of PB1 extrusion. Moreover, D4476 resulted in giant polar body extrusion, oocyte pro-MI arrest, chromosome congression failure and impairment of embryo developmental potential. In addition, we employed pyrvinium pamoate (PP), an allosteric activator of CK1α, to enhance CK1α activity in oocytes. Supplementation of PP induced oocyte meiotic maturation failure, severe congression abnormalities and misalignment of chromosomes. Taken together, our study for the first time demonstrates that CK1α is required for chromosome alignment and segregation during oocyte meiotic maturation and early embryo development.
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Affiliation(s)
- Lu Wang
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
| | - Angeleem Lu
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
| | - Hong-Xia Zhou
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
| | - Ran Sun
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
| | - Jie Zhao
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
| | - Cheng-Jie Zhou
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
| | - Jiang-Peng Shen
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
| | - Sha-Na Wu
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
| | - Cheng-Guang Liang
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
- * E-mail:
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Labrador L, Barroso C, Lightfoot J, Müller-Reichert T, Flibotte S, Taylor J, Moerman DG, Villeneuve AM, Martinez-Perez E. Chromosome movements promoted by the mitochondrial protein SPD-3 are required for homology search during Caenorhabditis elegans meiosis. PLoS Genet 2013; 9:e1003497. [PMID: 23671424 PMCID: PMC3649994 DOI: 10.1371/journal.pgen.1003497] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 03/21/2013] [Indexed: 11/29/2022] Open
Abstract
Pairing of homologous chromosomes during early meiosis is essential to prevent the formation of aneuploid gametes. Chromosome pairing includes a step of homology search followed by the stabilization of homolog interactions by the synaptonemal complex (SC). These events coincide with dramatic changes in nuclear organization and rapid chromosome movements that depend on cytoskeletal motors and are mediated by SUN-domain proteins on the nuclear envelope, but how chromosome mobility contributes to the pairing process remains poorly understood. We show that defects in the mitochondria-localizing protein SPD-3 cause a defect in homolog pairing without impairing nuclear reorganization or SC assembly, which results in promiscuous installation of the SC between non-homologous chromosomes. Preventing SC assembly in spd-3 mutants does not improve homolog pairing, demonstrating that SPD-3 is required for homology search at the start of meiosis. Pairing center regions localize to SUN-1 aggregates at meiosis onset in spd-3 mutants; and pairing-promoting proteins, including cytoskeletal motors and polo-like kinase 2, are normally recruited to the nuclear envelope. However, quantitative analysis of SUN-1 aggregate movement in spd-3 mutants demonstrates a clear reduction in mobility, although this defect is not as severe as that seen in sun-1(jf18) mutants, which also show a stronger pairing defect, suggesting a correlation between chromosome-end mobility and the efficiency of pairing. SUN-1 aggregate movement is also impaired following inhibition of mitochondrial respiration or dynein knockdown, suggesting that mitochondrial function is required for motor-driven SUN-1 movement. The reduced chromosome-end mobility of spd-3 mutants impairs coupling of SC assembly to homology recognition and causes a delay in meiotic progression mediated by HORMA-domain protein HTP-1. Our work reveals how chromosome mobility impacts the different early meiotic events that promote homolog pairing and suggests that efficient homology search at the onset of meiosis is largely dependent on motor-driven chromosome movement. Sexually reproducing organisms carry two copies of each chromosome (homologs), which must be separated during gamete formation to prevent chromosome duplication in each generation. This chromosome halving is achieved during meiosis, a type of cell division in which the homologs recognize and pair with one another before they become intimately glued together by a structure called the synaptonemal complex (SC). Homolog pairing and SC assembly coincide with movement of chromosomes inside the nucleus, but how chromosome mobility impacts these events is not understood. We find that the mitochondrial protein SPD-3 is required to ensure normal levels of motor-driven chromosome movement and that, although pairing-promoting proteins are normally recruited at the start of meiosis in spd-3 mutants, reduced chromosome mobility impairs homolog pairing. In contrast, SC assembly is normally started, leading to the installation of SC between non-homologous chromosomes and demonstrating a failure in the coordination of pairing and SC assembly. Reduced movement also causes a controlled delay in exit from early meiotic stages characterized by chromosome clustering and active homology search. Our findings show how the different events that lead to the correct association of homologous chromosomes during early meiosis are affected by chromosome mobility.
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Affiliation(s)
- Leticia Labrador
- MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, London, United Kingdom
| | - Consuelo Barroso
- MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, London, United Kingdom
| | - James Lightfoot
- MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, London, United Kingdom
| | | | - Stephane Flibotte
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Jon Taylor
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Donald G. Moerman
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Anne M. Villeneuve
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Enrique Martinez-Perez
- MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, London, United Kingdom
- * E-mail:
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229
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Bulankova P, Akimcheva S, Fellner N, Riha K. Identification of Arabidopsis meiotic cyclins reveals functional diversification among plant cyclin genes. PLoS Genet 2013; 9:e1003508. [PMID: 23671425 PMCID: PMC3649987 DOI: 10.1371/journal.pgen.1003508] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 03/26/2013] [Indexed: 11/18/2022] Open
Abstract
Meiosis is a modified cell division in which a single S-phase is followed by two rounds of chromosome segregation resulting in the production of haploid gametes. The meiotic mode of chromosome segregation requires extensive remodeling of the basic cell cycle machinery and employment of unique regulatory mechanisms. Cyclin-dependent kinases (CDKs) and cyclins represent an ancient molecular module that drives and regulates cell cycle progression. The cyclin gene family has undergone a massive expansion in angiosperm plants, but only a few cyclins were thoroughly characterized. In this study we performed a systematic immunolocalization screen to identify Arabidopsis thaliana A- and B-type cyclins expressed in meiosis. Many of these cyclins exhibit cell-type-specific expression in vegetative tissues and distinct subcellular localization. We found six A-type cyclins and a single B-type cyclin (CYCB3;1) to be expressed in male meiosis. Mutant analysis revealed that these cyclins contribute to distinct meiosis-related processes. While A2 cyclins are important for chromosome segregation, CYCB3;1 prevents ectopic cell wall formation. We further show that cyclin SDS does not contain a D-box and is constitutively expressed throughout meiosis. Analysis of plants carrying cyclin SDS with an introduced D-box motif determined that, in addition to its function in recombination, SDS acts together with CYCB3;1 in suppressing unscheduled cell wall synthesis. Our phenotypic and expression data provide extensive evidence that multiplication of cyclins is in plants accompanied by functional diversification. The alteration of haploid and diploid cell generations during the sexual life cycle requires meiosis, a specialized cell division that enables the formation of haploid gametes from diploid cells. Meiosis occurs only once during the life cycle, and the transition from the mitotic to meiotic mode of chromosome partitioning requires extensive remodeling of the cell cycle machinery. The cell cycle progression is driven by cyclin-dependent kinases and associated cyclins that regulate CDK activity and confer substrate specificity. Cyclin gene families have undergone a massive expansion in plants, which has raised the question of whether some of these cyclins evolved specific meiotic functions. We systematically analyzed two cyclin gene families in Arabidopsis to identify plant cyclins that are meiotically expressed. We found in total eight cyclins to be expressed in male meiotic cells, and functional characterization revealed their involvement in diverse meiotic processes. Interestingly, none of the cyclins appear to be essential for meiotic progression, indicating that plant meiosis is governed by unorthodox cell cycle regulators.
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Affiliation(s)
- Petra Bulankova
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna, Austria
| | | | - Nicole Fellner
- Campus Science Support Facilities, Electron Microscopy Facility, Vienna, Austria
| | - Karel Riha
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna, Austria
- * E-mail:
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230
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Shinohara M, Shinohara A. Multiple pathways suppress non-allelic homologous recombination during meiosis in Saccharomyces cerevisiae. PLoS One 2013; 8:e63144. [PMID: 23646187 PMCID: PMC3639938 DOI: 10.1371/journal.pone.0063144] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2012] [Accepted: 04/02/2013] [Indexed: 12/04/2022] Open
Abstract
Recombination during meiosis in the form of crossover events promotes the segregation of homologous chromosomes by providing the only physical linkage between these chromosomes. Recombination occurs not only between allelic sites but also between non-allelic (ectopic) sites. Ectopic recombination is often suppressed to prevent non-productive linkages. In this study, we examined the effects of various mutations in genes involved in meiotic recombination on ectopic recombination during meiosis. RAD24, a DNA damage checkpoint clamp-loader gene, suppressed ectopic recombination in wild type in the same pathway as RAD51. In the absence of RAD24, a meiosis-specific recA homolog, DMC1, suppressed the recombination. Homology search and strand exchange in ectopic recombination occurred when either the RAD51 or the DMC1 recA homolog was absent, but was promoted by RAD52. Unexpectedly, the zip1 mutant, which is defective in chromosome synapsis, showed a decrease, rather than an increase, in ectopic recombination. Our results provide evidence for two types of ectopic recombination: one that occurs in wild-type cells and a second that occurs predominantly when the checkpoint pathway is inactivated.
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Affiliation(s)
- Miki Shinohara
- Division of Integrated Protein Functions, Institute for Protein Research, Osaka University, Suita, Osaka, Japan
- Department of Biological Sciences, Graduate School of Science, Osaka University, Suita, Osaka, Japan
| | - Akira Shinohara
- Division of Integrated Protein Functions, Institute for Protein Research, Osaka University, Suita, Osaka, Japan
- Department of Biological Sciences, Graduate School of Science, Osaka University, Suita, Osaka, Japan
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231
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Wassmann K. Sister chromatid segregation in meiosis II: deprotection through phosphorylation. Cell Cycle 2013; 12:1352-9. [PMID: 23574717 DOI: 10.4161/cc.24600] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Meiotic divisions (meiosis I and II) are specialized cell divisions to generate haploid gametes. The first meiotic division with the separation of chromosomes is named reductional division. The second division, which takes place immediately after meiosis I without intervening S-phase, is equational, with the separation of sister chromatids, similar to mitosis. This meiotic segregation pattern requires the two-step removal of the cohesin complex holding sister chromatids together: cohesin is removed from chromosome arms that have been subjected to homologous recombination in meiosis I and from the centromere region in meiosis II. Cohesin in the centromere region is protected from removal in meiosis I, but this protection has to be removed--deprotected--for sister chromatid segregation in meiosis II. Whereas the mechanisms of cohesin protection are quite well understood, the mechanisms of deprotection have been largely unknown until recently. In this review I summarize our current knowledge on cohesin deprotection.
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232
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Guiraldelli MF, Eyster C, Wilkerson JL, Dresser ME, Pezza RJ. Mouse HFM1/Mer3 is required for crossover formation and complete synapsis of homologous chromosomes during meiosis. PLoS Genet 2013; 9:e1003383. [PMID: 23555294 PMCID: PMC3605105 DOI: 10.1371/journal.pgen.1003383] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 01/30/2013] [Indexed: 12/31/2022] Open
Abstract
Faithful chromosome segregation during meiosis requires that homologous chromosomes associate and recombine. Chiasmata, the cytological manifestation of recombination, provide the physical link that holds the homologs together as a pair, facilitating their orientation on the spindle at meiosis I. Formation of most crossover (CO) events requires the assistance of a group of proteins collectively known as ZMM. HFM1/Mer3 is in this group of proteins and is required for normal progression of homologous recombination and proper synapsis between homologous chromosomes in a number of model organisms. Our work is the first study in mammals showing the in vivo function of mouse HFM1. Cytological observations suggest that initial steps of recombination are largely normal in a majority of Hfm1(-/-) spermatocytes. Intermediate and late stages of recombination appear aberrant, as chromosomal localization of MSH4 is altered and formation of MLH1foci is drastically reduced. In agreement, chiasma formation is reduced, and cells arrest with subsequent apoptosis at diakinesis. Our results indicate that deletion of Hfm1 leads to the elimination of a major fraction but not all COs. Formation of chromosome axial elements and homologous pairing is apparently normal, and Hfm1(-/-) spermatocytes progress to the end of prophase I without apparent developmental delay or apoptosis. However, synapsis is altered with components of the central region of the synaptonemal complex frequently failing to extend the full length of the chromosome axes. We propose that initial steps of recombination are sufficient to support homology recognition, pairing, and initial chromosome synapsis and that HFM1 is required to form normal numbers of COs and to complete synapsis.
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Affiliation(s)
- Michel F. Guiraldelli
- Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - Craig Eyster
- Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - Joseph L. Wilkerson
- Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
- Department of Cell Biology, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma, United States of America
| | - Michael E. Dresser
- Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
- Department of Cell Biology, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma, United States of America
| | - Roberto J. Pezza
- Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
- Department of Cell Biology, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma, United States of America
- * E-mail:
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233
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Howard-Till RA, Lukaszewicz A, Novatchkova M, Loidl J. A single cohesin complex performs mitotic and meiotic functions in the protist tetrahymena. PLoS Genet 2013; 9:e1003418. [PMID: 23555314 PMCID: PMC3610610 DOI: 10.1371/journal.pgen.1003418] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 02/12/2013] [Indexed: 01/08/2023] Open
Abstract
The cohesion of sister chromatids in the interval between chromosome replication and anaphase is important for preventing the precocious separation, and hence nondisjunction, of chromatids. Cohesion is accomplished by a ring-shaped protein complex, cohesin; and its release at anaphase occurs when separase cleaves the complex's α-kleisin subunit. Cohesin has additional roles in facilitating DNA damage repair from the sister chromatid and in regulating gene expression. We tested the universality of the present model of cohesion by studying cohesin in the evolutionarily distant protist Tetrahymena thermophila. Localization of tagged cohesin components Smc1p and Rec8p (the α-kleisin) showed that cohesin is abundant in mitotic and meiotic nuclei. RNAi knockdown experiments demonstrated that cohesin is crucial for normal chromosome segregation and meiotic DSB repair. Unexpectedly, cohesin does not detach from chromosome arms in anaphase, yet chromosome segregation depends on the activity of separase (Esp1p). When Esp1p is depleted by RNAi, chromosomes become polytenic as they undergo multiple rounds of replication, but fail to separate. The cohesion of such bundles of numerous chromatids suggests that chromatids may be connected by factors in addition to topological linkage by cohesin rings. Although cohesin is not detected in transcriptionally active somatic nuclei, its loss causes a slight defect in their amitotic division. Notably, Tetrahymena uses a single version of α-kleisin for both mitosis and meiosis. Therefore, we propose that the differentiation of mitotic and meiotic cohesins found in most other model systems is not due to the need of a specialized meiotic cohesin, but due to additional roles of mitotic cohesin.
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Affiliation(s)
- Rachel A. Howard-Till
- Department of Chromosome Biology and Max F. Perutz Laboratories, Center for Molecular Biology, University of Vienna, Vienna, Austria
| | - Agnieszka Lukaszewicz
- Department of Chromosome Biology and Max F. Perutz Laboratories, Center for Molecular Biology, University of Vienna, Vienna, Austria
| | - Maria Novatchkova
- Research Institute of Molecular Pathology (IMP), Vienna, Austria
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
| | - Josef Loidl
- Department of Chromosome Biology and Max F. Perutz Laboratories, Center for Molecular Biology, University of Vienna, Vienna, Austria
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234
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Calvente A, Viera A, Parra MT, de la Fuente R, Suja JA, Page J, Santos JL, de la Vega CG, Barbero JL, Rufas JS. Dynamics of cohesin subunits in grasshopper meiotic divisions. Chromosoma 2013; 122:77-91. [PMID: 23283389 DOI: 10.1007/s00412-012-0393-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 11/08/2012] [Accepted: 12/01/2012] [Indexed: 01/18/2023]
Abstract
The cohesin complex plays a key role for the maintenance of sister chromatid cohesion and faithful chromosome segregation in both mitosis and meiosis. This complex is formed by two structural maintenance of chromosomes protein family (SMC) subunits and two non-SMC subunits: an α-kleisin subunit SCC1/RAD21/REC8 and an SCC3-like protein. Several studies carried out in different species have revealed that the distribution of the cohesin subunits along the chromosomes during meiotic prophase I is not regular and that some subunits are distinctly incorporated at different cell stages. However, the accurate distribution of the different cohesin subunits in condensed meiotic chromosomes is still controversial. Here, we describe the dynamics of the cohesin subunits SMC1α, SMC3, RAD21 and SA1 during both meiotic divisions in grasshoppers. Although these subunits show a similar patched labelling at the interchromatid domain of metaphase I bivalents, SMCs and non-SMCs subunits do not always colocalise. Indeed, SA1 is the only cohesin subunit accumulated at the centromeric region of all metaphase I chromosomes. Additionally, non-SMC subunits do not appear at the interchromatid domain in either single X or B chromosomes. These data suggest the existence of several cohesin complexes during metaphase I. The cohesin subunits analysed are released from chromosomes at the beginning of anaphase I, with the exception of SA1 which can be detected at the centromeres until telophase II. These observations indicate that the cohesin components may be differentially loaded and released from meiotic chromosomes during the first and second meiotic divisions. The roles of these cohesin complexes for the maintenance of chromosome structure and their involvement in homologous segregation at first meiotic division are proposed and discussed.
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Affiliation(s)
- A Calvente
- Departamento de Biología, Facultad de Ciencias, Edificio de Biológicas, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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235
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Qi ST, Wang ZB, Ouyang YC, Zhang QH, Hu MW, Huang X, Ge Z, Guo L, Wang YP, Hou Y, Schatten H, Sun QY. Overexpression of SETβ, a protein localizing to centromeres, causes precocious separation of chromatids during the first meiosis of mouse oocytes. J Cell Sci 2013; 126:1595-603. [PMID: 23444375 DOI: 10.1242/jcs.116541] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Chromosome segregation in mammalian oocyte meiosis is an error-prone process, and any mistake in this process may result in aneuploidy, which is the main cause of infertility, abortion and many genetic diseases. It is now well known that shugoshin and protein phosphatase 2A (PP2A) play important roles in the protection of centromeric cohesion during the first meiosis. PP2A can antagonize the phosphorylation of rec8, a member of the cohesin complex, at the centromeres and thus prevent cleavage of rec8 and so maintain the cohesion of chromatids. SETβ is a protein that physically interacts with shugoshin and inhibits PP2A activity. We thus hypothesized that SETβ might regulate cohesion protection and chromosome segregation during oocyte meiotic maturation. Here we report for the first time the expression, subcellular localization and functions of SETβ during mouse oocyte meiosis. Immunoblotting analysis showed that the expression level of SETβ was stable from the germinal vesicle stage to the MII stage of oocyte meiosis. Immunofluorescence analysis showed SETβ accumulation in the nucleus at the germinal vesicle stage, whereas it was targeted mainly to the inner centromere area and faintly localized to the interchromatid axes from germinal vesicle breakdown to MI stages. At the MII stage, SETβ still localized to the inner centromere area, but could relocalize to kinetochores in a process perhaps dependent on the tension on the centromeres. SETβ partly colocalized with PP2A at the inner centromere area. Overexpression of SETβ in mouse oocytes caused precocious separation of sister chromatids, but depletion of SETβ by RNAi showed little effects on the meiotic maturation process. Taken together, our results suggest that SETβ, even though it localizes to centromeres, might not be essential for chromosome separation during mouse oocyte meiotic maturation, although its forced overexpression causes premature chromatid separation.
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Affiliation(s)
- Shu-Tao Qi
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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236
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The PP2A inhibitor I2PP2A is essential for sister chromatid segregation in oocyte meiosis II. Curr Biol 2013; 23:485-90. [PMID: 23434280 DOI: 10.1016/j.cub.2013.02.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 01/02/2013] [Accepted: 02/01/2013] [Indexed: 11/20/2022]
Abstract
Haploid gametes are generated through two consecutive meiotic divisions, with the segregation of chromosome pairs in meiosis I and sister chromatids in meiosis II. Separase-mediated stepwise removal of cohesion, first from chromosome arms and later from the centromere region, is a prerequisite for maintaining sister chromatids together until their separation in meiosis II [1]. In all model organisms, centromeric cohesin is protected from separase-dependent removal in meiosis I through the activity of PP2A-B56 phosphatase, which is recruited to centromeres by shugoshin/MEI-S332 (Sgo) [2-5]. How this protection of centromeric cohesin is removed in meiosis II is not entirely clear; we find that all the PP2A subunits remain colocalized with the cohesin subunit Rec8 at the centromere of metaphase II chromosomes. Here, we show that sister chromatid separation in oocytes depends on a PP2A inhibitor, namely I2PP2A. I2PP2A colocalizes with the PP2A enzyme at centromeres at metaphase II, independently of bipolar attachment. When I2PP2A is depleted, sister chromatids fail to segregate during meiosis II. Our findings demonstrate that in oocytes I2PP2A is essential for faithful sister chromatid segregation by mediating deprotection of centromeric cohesin in meiosis II.
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237
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Yajima M, Suglia E, Gustafson EA, Wessel GM. Meiotic gene expression initiates during larval development in the sea urchin. Dev Dyn 2013; 242:155-63. [PMID: 23172739 PMCID: PMC3553291 DOI: 10.1002/dvdy.23904] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2012] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Meiosis is a unique mechanism in gamete production and a fundamental process shared by all sexually reproducing eukaryotes. Meiosis requires several specialized and highly conserved genes whose expression can also identify the germ cells undergoing gametogenic differentiation. Sea urchins are echinoderms, which form a phylogenetic sister group of chordates. Sea urchin embryos undergo a feeding, planktonic larval phase in which they construct an adult rudiment prior to metamorphosis. Although a series of conserved meiosis genes (e.g., dmc1, msh5, rad21, rad51, and sycp1) is expressed in sea urchin oocytes, we sought to determine when in development meiosis would first be initiated. RESULTS We surveyed the expression of several meiotic genes and their corresponding proteins in the sea urchin Strongylocentrotus purpuratus. Surprisingly, meiotic genes are highly expressed not only in ovaries but beginning in larvae. Both RNA and protein localizations strongly suggest that meiotic gene expression initiates in tissues that will eventually give rise to the adult rudiment of the late larva. CONCLUSIONS These results demonstrate that broad expression of the molecules associated with meiotic differentiation initiates prior to metamorphosis and may have additional functions in these cells, or mechanisms repressing their function, until later in development when gametogenesis begins.
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Affiliation(s)
- Mamiko Yajima
- MCB Department, Brown University, 185 Meeting Street, BOX-GL173, Providence, RI 02912, USA
| | - Elena Suglia
- MCB Department, Brown University, 185 Meeting Street, BOX-GL173, Providence, RI 02912, USA
| | - Eric A. Gustafson
- MCB Department, Brown University, 185 Meeting Street, BOX-GL173, Providence, RI 02912, USA
| | - Gary M. Wessel
- MCB Department, Brown University, 185 Meeting Street, BOX-GL173, Providence, RI 02912, USA
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238
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Okaz E, Argüello-Miranda O, Bogdanova A, Vinod PK, Lipp JJ, Markova Z, Zagoriy I, Novak B, Zachariae W. Meiotic prophase requires proteolysis of M phase regulators mediated by the meiosis-specific APC/CAma1. Cell 2013; 151:603-18. [PMID: 23101628 DOI: 10.1016/j.cell.2012.08.044] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 06/24/2012] [Accepted: 08/15/2012] [Indexed: 12/13/2022]
Abstract
Whereas proliferating cells enter M phase shortly after DNA replication, the first M phase of meiosis is preceded by an extended prophase in which homologous chromosomes undergo recombination. Exit from prophase I is controlled by the recombination checkpoint (RC), which, in yeast, represses the meiosis-specific transcription factor Ndt80 required for the expression of B-type cyclins and other M phase regulators. We show that an extended prophase I additionally requires the suppression of latent, mitotic cell-cycle controls by the anaphase-promoting complex (APC/C) and its meiosis-specific activator Ama1, which trigger the degradation of M phase regulators and Ndd1, a subunit of a mitotic transcription factor. ama1Δ mutants exit from prophase I prematurely and independently of the RC, which results in recombination defects and chromosome missegregation. Thus, control of prophase I by meiotic mechanisms depends on the suppression of the alternative, mitotic mechanisms by a meiosis-specific form of the APC/C.
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Affiliation(s)
- Elwy Okaz
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
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239
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Trickey M, Fujimitsu K, Yamano H. Anaphase-promoting complex/cyclosome-mediated proteolysis of Ams2 in the G1 phase ensures the coupling of histone gene expression to DNA replication in fission yeast. J Biol Chem 2013; 288:928-37. [PMID: 23195958 PMCID: PMC3543042 DOI: 10.1074/jbc.m112.410241] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 11/20/2012] [Indexed: 01/12/2023] Open
Abstract
Histone transcription and deposition are tightly regulated with the DNA replication cycle to maintain genetic integrity. Ams2 is a GATA-containing transcription factor responsible for core histone gene expression and for CENP-A loading at centromeres in fission yeast. Ams2 levels are cell cycle-regulated, and after the S phase Ams2 is degraded by the SCF(pof3) ubiquitin ligase; however, the regulation of Ams2 in G(1) or meiosis is poorly understood. Here we show that another ubiquitin ligase, the anaphase-promoting complex/cyclosome (APC/C) targets Ams2 for destruction in G(1). Ubiquitylation and destruction of Ams2 is dependent upon a coactivator Cdh1/Ste9 and the KEN box in the C terminus of Ams2. We also find that stabilization of Ams2 sensitizes cells to the anti-microtubule drug thiabendazole and the histone deacetylase inhibitor tricostatin A when a histone deacetylase gene hst4 is deleted, suggesting that histone acetylation together with Ams2 stability ensures the coupling of mitosis to DNA replication. Furthermore, in meiosis, the failure of the APC/C-mediated destruction of Ams2 is deleterious, and pre-meiotic DNA replication is barely completed. These data suggest that Ams2 destruction via both the APC/C and the SCF ubiquitin ligases underlies the coordination of histone expression and DNA replication.
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Affiliation(s)
- Michelle Trickey
- From the Cell Cycle Control Group, University College London Cancer Institute, WC1E 6BT, United Kingdom
| | - Kazuyuki Fujimitsu
- From the Cell Cycle Control Group, University College London Cancer Institute, WC1E 6BT, United Kingdom
| | - Hiroyuki Yamano
- From the Cell Cycle Control Group, University College London Cancer Institute, WC1E 6BT, United Kingdom
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240
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Humphryes N, Leung WK, Argunhan B, Terentyev Y, Dvorackova M, Tsubouchi H. The Ecm11-Gmc2 complex promotes synaptonemal complex formation through assembly of transverse filaments in budding yeast. PLoS Genet 2013; 9:e1003194. [PMID: 23326245 PMCID: PMC3542071 DOI: 10.1371/journal.pgen.1003194] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 11/10/2012] [Indexed: 11/19/2022] Open
Abstract
During meiosis, homologous chromosomes pair at close proximity to form the synaptonemal complex (SC). This association is mediated by transverse filament proteins that hold the axes of homologous chromosomes together along their entire length. Transverse filament proteins are highly aggregative and can form an aberrant aggregate called the polycomplex that is unassociated with chromosomes. Here, we show that the Ecm11-Gmc2 complex is a novel SC component, functioning to facilitate assembly of the yeast transverse filament protein, Zip1. Ecm11 and Gmc2 initially localize to the synapsis initiation sites, then throughout the synapsed regions of paired homologous chromosomes. The absence of either Ecm11 or Gmc2 substantially compromises the chromosomal assembly of Zip1 as well as polycomplex formation, indicating that the complex is required for extensive Zip1 polymerization. We also show that Ecm11 is SUMOylated in a Gmc2-dependent manner. Remarkably, in the unSUMOylatable ecm11 mutant, assembly of chromosomal Zip1 remained compromised while polycomplex formation became frequent. We propose that the Ecm11-Gmc2 complex facilitates the assembly of Zip1 and that SUMOylation of Ecm11 is critical for ensuring chromosomal assembly of Zip1, thus suppressing polycomplex formation. Meiosis is central to the life cycle of sexually reproducing organisms. The first round of division (meiosis I) is unique to meiosis in that homologous chromosomes are segregated to opposite poles. The tight association between homologous chromosomes is essential for their faithful segregation. To establish such association, meiosis employs a unique, homologous recombination-dependent mechanism that facilitates the recognition, association, and reciprocal exchange of DNA strands of homologous chromosomes, thus providing physical connections between homologous chromosomes. All these events take place in the context of an intricate structure called the synaptonemal complex (SC). Within this complex, the axis of one chromosome is aligned at close proximity with the axis of its homologue. This alignment stretches along the entire length of the chromosome pair, with zipper-like structures, called transverse filaments, holding axes together. In this work, we identified the Ecm11-Gmc2 complex as a novel component of the SC, promoting the assembly of transverse filaments. Importantly, we demonstrate that post-translational modification of Ecm11 with SUMO (small ubiquitin-like modifier) is critical for ensuring the chromosomal loading of transverse filaments. Thus, our work provides a molecular basis for how homologous chromosomes become tightly associated during meiotic prophase.
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Affiliation(s)
- Neil Humphryes
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Wing-Kit Leung
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Bilge Argunhan
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Yaroslav Terentyev
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Martina Dvorackova
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Hideo Tsubouchi
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
- * E-mail:
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241
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Lu S, Zong C, Fan W, Yang M, Li J, Chapman AR, Zhu P, Hu X, Xu L, Yan L, Bai F, Qiao J, Tang F, Li R, Xie XS. Probing meiotic recombination and aneuploidy of single sperm cells by whole-genome sequencing. Science 2013; 338:1627-30. [PMID: 23258895 DOI: 10.1126/science.1229112] [Citation(s) in RCA: 224] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Meiotic recombination creates genetic diversity and ensures segregation of homologous chromosomes. Previous population analyses yielded results averaged among individuals and affected by evolutionary pressures. We sequenced 99 sperm from an Asian male by using the newly developed amplification method-multiple annealing and looping-based amplification cycles-to phase the personal genome and map recombination events at high resolution, which are nonuniformly distributed across the genome in the absence of selection pressure. The paucity of recombination near transcription start sites observed in individual sperm indicates that such a phenomenon is intrinsic to the molecular mechanism of meiosis. Interestingly, a decreased crossover frequency combined with an increase of autosomal aneuploidy is observable on a global per-sperm basis.
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Affiliation(s)
- Sijia Lu
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
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242
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Abstract
This chapter describes a technique for performing chromosome spreads from mouse oocytes. It is based on a previously described protocol (Hodges and Hunt, Chromosoma 111: 165-169, 2002), which we have modified. Chromosomes are stained with either Propidium Iodide or Hoechst. This spreading technique allows for simultaneous immunostaining of proteins associated with chromosomes. It is very useful to stain spreads with CREST serum which labels kinetochores, to be able to distinguish bivalents (chromosome pairs), dyads or univalents (paired sister chromatids), and single sister chromatids without ambiguity.
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243
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Walker CW, Lesser M, Unuma T. Sea Urchin Gametogenesis – Structural, Functional and Molecular/Genomic Biology. DEVELOPMENTS IN AQUACULTURE AND FISHERIES SCIENCE 2013. [DOI: 10.1016/b978-0-12-396491-5.00003-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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244
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Karess RE, Wassmann K, Rahmani Z. New insights into the role of BubR1 in mitosis and beyond. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 306:223-73. [PMID: 24016527 DOI: 10.1016/b978-0-12-407694-5.00006-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
BubR1 is a critical component of the spindle assembly checkpoint, the surveillance mechanism that helps maintain the high fidelity of mitotic chromosome segregation by preventing cells from initiating anaphase if one or more kinetochores are not attached to the spindle. BubR1 also helps promote the establishment of stable kinetochore-microtubule attachments during prometaphase. In this chapter, we review the structure, functions, and regulation of BubR1 in these "classical roles" at the kinetochore. We discuss its recruitment to kinetochores, its assembly into the inhibitor of anaphase progression, and the importance of its posttranslational modifications. We also consider the evidence for its participation in other roles beyond mitosis, such as the meiosis-specific processes of recombination and prophase arrest of the first meiotic division, the cellular response to DNA damage, and in the regulation of centrosome and basal body function. Finally, studies are presented linking BubR1 dysfunction or misregulation to aging and human disease, particularly cancer.
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Affiliation(s)
- Roger E Karess
- Institut Jacques Monod, UMR 7592 CNRS, Université Paris Diderot-Paris 7, Paris, France.
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245
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Toyoizumi H, Tsubouchi H. Estimating the number of double-strand breaks formed during meiosis from partial observation. J Comput Biol 2012; 19:1277-83. [PMID: 23210475 DOI: 10.1089/cmb.2012.0209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Analyzing the basic mechanism of DNA double-strand breaks (DSB) formation during meiosis is important for understanding sexual reproduction and genetic diversity. The location and amount of meiotic DSBs can be examined by using a common molecular biological technique called Southern blotting, but only a subset of the total DSBs can be observed; only DSB fragments still carrying the region recognized by a Southern blot probe are detected. With the assumption that DSB formation follows a nonhomogeneous Poisson process, we propose two estimators of the total number of DSBs on a chromosome: (1) an estimator based on the Nelson-Aalen estimator, and (2) an estimator based on a record value process. Further, we compared their asymptotic accuracy.
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246
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Berkowitz KM, Sowash AR, Koenig LR, Urcuyo D, Khan F, Yang F, Wang PJ, Jongens TA, Kaestner KH. Disruption of CHTF18 causes defective meiotic recombination in male mice. PLoS Genet 2012; 8:e1002996. [PMID: 23133398 PMCID: PMC3486840 DOI: 10.1371/journal.pgen.1002996] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 08/13/2012] [Indexed: 12/23/2022] Open
Abstract
CHTF18 (chromosome transmission fidelity factor 18) is an evolutionarily conserved subunit of the Replication Factor C-like complex, CTF18-RLC. CHTF18 is necessary for the faithful passage of chromosomes from one daughter cell to the next during mitosis in yeast, and it is crucial for germline development in the fruitfly. Previously, we showed that mouse Chtf18 is expressed throughout the germline, suggesting a role for CHTF18 in mammalian gametogenesis. To determine the role of CHTF18 in mammalian germ cell development, we derived mice carrying null and conditional mutations in the Chtf18 gene. Chtf18-null males exhibit 5-fold decreased sperm concentrations compared to wild-type controls, resulting in subfertility. Loss of Chtf18 results in impaired spermatogenesis; spermatogenic cells display abnormal morphology, and the stereotypical arrangement of cells within seminiferous tubules is perturbed. Meiotic recombination is defective and homologous chromosomes separate prematurely during prophase I. Repair of DNA double-strand breaks is delayed and incomplete; both RAD51 and γH2AX persist in prophase I. In addition, MLH1 foci are decreased in pachynema. These findings demonstrate essential roles for CHTF18 in mammalian spermatogenesis and meiosis, and suggest that CHTF18 may function during the double-strand break repair pathway to promote the formation of crossovers. Meiosis is the specialized process of cell division during germ cell development that results in formation of eggs and sperm. Genetic exchange between maternal and paternal chromosomes occurs during meiosis in a process called homologous recombination, in which DNA double- strand breaks are made and then repaired to allow DNA crossovers to form. These are essential processes that keep homologous chromosomes joined until anaphase I and ensure proper chromosome segregation. Errors in meiotic recombination lead to chromosome mis-segregation and ultimately aneuploidy, an abnormal chromosome number. Although it is well known that defects in these processes contribute greatly to infertility, birth defects, and pregnancy loss in humans, their molecular basis is not well understood. We demonstrate here a Chtf18 mutant mouse that exhibits subfertility and defects in meiotic recombination. Specifically, DNA double-strand breaks are incompletely repaired, DNA crossovers are significantly decreased, and homologous chromosomes separate during prophase I in Chtf18-null males. Our findings suggest roles for CHTF18 in DNA double-strand break repair and crossover formation, functions in mammals not previously known.
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Affiliation(s)
- Karen M Berkowitz
- Department of Obstetrics and Gynecology, Drexel University College of Medicine, Philadelphia, PA, USA.
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247
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Touati SA, Cladière D, Lister LM, Leontiou I, Chambon JP, Rattani A, Böttger F, Stemmann O, Nasmyth K, Herbert M, Wassmann K. Cyclin A2 is required for sister chromatid segregation, but not separase control, in mouse oocyte meiosis. Cell Rep 2012; 2:1077-87. [PMID: 23122964 DOI: 10.1016/j.celrep.2012.10.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 09/04/2012] [Accepted: 10/02/2012] [Indexed: 11/18/2022] Open
Abstract
In meiosis, two specialized cell divisions allow the separation of paired chromosomes first, then of sister chromatids. Separase removes the cohesin complex holding sister chromatids together in a stepwise manner from chromosome arms in meiosis I, then from the centromere region in meiosis II. Using mouse oocytes, our study reveals that cyclin A2 promotes entry into meiosis, as well as an additional unexpected role; namely, its requirement for separase-dependent sister chromatid separation in meiosis II. Untimely cyclin A2-associated kinase activity in meiosis I leads to precocious sister separation, whereas inhibition of cyclin A2 in meiosis II prevents it. Accordingly, endogenous cyclin A is localized to kinetochores throughout meiosis II, but not in anaphase I. Additionally, we found that cyclin B1, but not cyclin A2, inhibits separase in meiosis I. These findings indicate that separase-dependent cohesin removal is differentially regulated by cyclin B1 and A2 in mammalian meiosis.
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Affiliation(s)
- Sandra A Touati
- UPMC Université Paris 06, UMR7622 Laboratoire de Biologie du Développement, 9 quai St. Bernard, Paris 75005, France
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248
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Abstract
Condensins are multisubunit protein complexes that play a fundamental role in the structural and functional organization of chromosomes in the three domains of life. Most eukaryotic species have two different types of condensin complexes, known as condensins I and II, that fulfill nonoverlapping functions and are subjected to differential regulation during mitosis and meiosis. Recent studies revealed that the two complexes contribute to a wide variety of interphase chromosome functions, such as gene regulation, recombination, and repair. Also emerging are their cell type- and tissue-specific functions and relevance to human disease. Biochemical and structural analyses of eukaryotic and bacterial condensins steadily uncover the mechanisms of action of this class of highly sophisticated molecular machines. Future studies on condensins will not only enhance our understanding of chromosome architecture and dynamics, but also help address a previously underappreciated yet profound set of questions in chromosome biology.
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Affiliation(s)
- Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN Advanced Science Institute, Wako, Saitama, Japan.
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249
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Liu W, Yin J, Zhao G, Yun Y, Wu S, Jones K, Lei A. Differential regulation of cyclin B1 degradation between the first and second meiotic divisions of bovine oocytes. Theriogenology 2012; 78:1171-81.e1. [DOI: 10.1016/j.theriogenology.2012.06.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 06/04/2012] [Accepted: 06/05/2012] [Indexed: 11/28/2022]
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250
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Zhao Y, Zhan Q. Electric fields generated by synchronized oscillations of microtubules, centrosomes and chromosomes regulate the dynamics of mitosis and meiosis. Theor Biol Med Model 2012; 9:26. [PMID: 22748065 PMCID: PMC3503562 DOI: 10.1186/1742-4682-9-26] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 06/26/2012] [Indexed: 12/23/2022] Open
Abstract
Super-macromolecular complexes play many important roles in eukaryotic cells. Classical structural biological studies focus on their complicated molecular structures, physical interactions and biochemical modifications. Recent advances concerning intracellular electric fields generated by cell organelles and super-macromolecular complexes shed new light on the mechanisms that govern the dynamics of mitosis and meiosis. In this review we synthesize this knowledge to provide an integrated theoretical model of these cellular events. We suggest that the electric fields generated by synchronized oscillation of microtubules, centrosomes, and chromatin fibers facilitate several events during mitosis and meiosis, including centrosome trafficking, chromosome congression in mitosis and synapsis between homologous chromosomes in meiosis. These intracellular electric fields are generated under energy excitation through the synchronized electric oscillations of the dipolar structures of microtubules, centrosomes and chromosomes, three of the super-macromolecular complexes within an animal cell.
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Affiliation(s)
- Yue Zhao
- State key laboratory of molecular oncology, Cancer Institute & Hospital of Chinese Academy of Medical Sciences, Peking Union Medical College, Room 6107, No,17 Pan Jia Yuan Nan Li, Chao Yang District, Bei Jing, 100021, China.
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