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Shugoshin forms a specialized chromatin domain at subtelomeres that regulates transcription and replication timing. Nat Commun 2016; 7:10393. [PMID: 26804021 PMCID: PMC4737732 DOI: 10.1038/ncomms10393] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 12/07/2015] [Indexed: 01/11/2023] Open
Abstract
A chromosome is composed of structurally and functionally distinct domains. However, the molecular mechanisms underlying the formation of chromatin structure and the function of subtelomeres, the telomere-adjacent regions, remain obscure. Here we report the roles of the conserved centromeric protein Shugoshin 2 (Sgo2) in defining chromatin structure and functions of the subtelomeres in the fission yeast Schizosaccharomyces pombe. We show that Sgo2 localizes at the subtelomeres preferentially during G2 phase and is essential for the formation of a highly condensed subtelomeric chromatin body 'knob'. Furthermore, the absence of Sgo2 leads to the derepression of the subtelomeric genes and premature DNA replication at the subtelomeric late origins. Thus, the subtelomeric specialized chromatin domain organized by Sgo2 represses both transcription and replication to ensure proper gene expression and replication timing.
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A Computational Approach to Estimating Nondisjunction Frequency in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2016; 6:669-82. [PMID: 26747203 PMCID: PMC4777129 DOI: 10.1534/g3.115.024380] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Errors segregating homologous chromosomes during meiosis result in aneuploid gametes and are the largest contributing factor to birth defects and spontaneous abortions in humans. Saccharomyces cerevisiae has long served as a model organism for studying the gene network supporting normal chromosome segregation. Measuring homolog nondisjunction frequencies is laborious, and involves dissecting thousands of tetrads to detect missegregation of individually marked chromosomes. Here we describe a computational method (TetFit) to estimate the relative contributions of meiosis I nondisjunction and random-spore death to spore inviability in wild type and mutant strains. These values are based on finding the best-fit distribution of 4, 3, 2, 1, and 0 viable-spore tetrads to an observed distribution. Using TetFit, we found that meiosis I nondisjunction is an intrinsic component of spore inviability in wild-type strains. We show proof-of-principle that the calculated average meiosis I nondisjunction frequency determined by TetFit closely matches empirically determined values in mutant strains. Using these published data sets, TetFit uncovered two classes of mutants: Class A mutants skew toward increased nondisjunction death, and include those with known defects in establishing pairing, recombination, and/or synapsis of homologous chromosomes. Class B mutants skew toward random spore death, and include those with defects in sister-chromatid cohesion and centromere function. Epistasis analysis using TetFit is facilitated by the low numbers of tetrads (as few as 200) required to compare the contributions to spore death in different mutant backgrounds. TetFit analysis does not require any special strain construction, and can be applied to previously observed tetrad distributions.
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The Dysferlin Domain-Only Protein, Spo73, Is Required for Prospore Membrane Extension in Saccharomyces cerevisiae. mSphere 2015; 1:mSphere00038-15. [PMID: 27303688 PMCID: PMC4863634 DOI: 10.1128/msphere.00038-15] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 11/18/2015] [Indexed: 01/11/2023] Open
Abstract
Sporulation of Saccharomyces cerevisiae is a developmental process in which an ascus containing four haploid spores forms from a diploid cell. During this process, newly formed membrane structures called prospore membranes extend along the nuclear envelope and engulf and package daughter nuclei along with cytosol and organelles to form precursors of spores. Proteins involved in prospore membrane extension, Vps13 and Spo71, have recently been reported; however, the overall mechanism of membrane extension remains unclear. Here, we identified Spo73 as an additional factor involved in prospore membrane extension. Analysis of a spo73∆ mutant revealed that it shows defects similar to those of a spo71∆ mutant during prospore membrane formation. Spo73 localizes to the prospore membrane, and this localization is independent of Spo71 and Vps13. In contrast, a Spo73 protein carrying mutations in a surface basic patch mislocalizes to the cytoplasm and overexpression of Spo71 can partially rescue localization to the prospore membrane. Similar to spo71∆ mutants, spo73∆ mutants display genetic interactions with the mutations in the SMA2 and SPO1 genes involved in prospore membrane bending. Further, our bioinformatic analysis revealed that Spo73 is a dysferlin domain-only protein. Thus, these results suggest that a dysferlin domain-only protein, Spo73, functions with a dual pleckstrin homology domain protein, Spo71, in prospore membrane extension. Analysis of Spo73 will provide insights into the conserved function of dysferlin domains, which is related to dysferlinopathy. IMPORTANCE Prospore membrane formation consists of de novo double-membrane formation, which occurs during the developmental process of sporulation in Saccharomyces cerevisiae. Membranes are formed into their proper size and shape, and thus, prospore membrane formation has been studied as a general model of membrane formation. We identified SPO73, previously shown to be required for spore wall formation, as an additional gene involved in prospore membrane extension. Genetic and cell biological analyses suggested that Spo73 functions on the prospore membrane with other factors in prospore membrane extension, counteracting the bending force of the prospore membrane. Spo73 is the first dysferlin domain-only protein ever analyzed. The dysferlin domain is conserved from yeast to mammals and is found in dysferlin proteins, which are involved in dysferlinopathy, although the precise function of the domain is unknown. Continued analysis of Spo73 will contribute to our understanding of the function of dysferlin domains and dysferlinopathy.
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Vincenten N, Kuhl LM, Lam I, Oke A, Kerr AR, Hochwagen A, Fung J, Keeney S, Vader G, Marston AL. The kinetochore prevents centromere-proximal crossover recombination during meiosis. eLife 2015. [PMID: 26653857 DOI: 10.7554/elife.10850.036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023] Open
Abstract
During meiosis, crossover recombination is essential to link homologous chromosomes and drive faithful chromosome segregation. Crossover recombination is non-random across the genome, and centromere-proximal crossovers are associated with an increased risk of aneuploidy, including Trisomy 21 in humans. Here, we identify the conserved Ctf19/CCAN kinetochore sub-complex as a major factor that minimizes potentially deleterious centromere-proximal crossovers in budding yeast. We uncover multi-layered suppression of pericentromeric recombination by the Ctf19 complex, operating across distinct chromosomal distances. The Ctf19 complex prevents meiotic DNA break formation, the initiating event of recombination, proximal to the centromere. The Ctf19 complex independently drives the enrichment of cohesin throughout the broader pericentromere to suppress crossovers, but not DNA breaks. This non-canonical role of the kinetochore in defining a chromosome domain that is refractory to crossovers adds a new layer of functionality by which the kinetochore prevents the incidence of chromosome segregation errors that generate aneuploid gametes.
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Affiliation(s)
- Nadine Vincenten
- The Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Lisa-Marie Kuhl
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Isabel Lam
- Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Ashwini Oke
- Department of Obstetrics, Gynecology and Reproductive Sciences, Center of Reproductive Sciences, University of California, San Francisco, San Francisco, United States
| | - Alastair Rw Kerr
- The Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | | | - Jennifer Fung
- Department of Obstetrics, Gynecology and Reproductive Sciences, Center of Reproductive Sciences, University of California, San Francisco, San Francisco, United States
| | - Scott Keeney
- Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Gerben Vader
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Adèle L Marston
- The Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
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Vincenten N, Kuhl LM, Lam I, Oke A, Kerr AR, Hochwagen A, Fung J, Keeney S, Vader G, Marston AL. The kinetochore prevents centromere-proximal crossover recombination during meiosis. eLife 2015; 4. [PMID: 26653857 PMCID: PMC4749563 DOI: 10.7554/elife.10850] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 12/13/2015] [Indexed: 11/13/2022] Open
Abstract
During meiosis, crossover recombination is essential to link homologous chromosomes and drive faithful chromosome segregation. Crossover recombination is non-random across the genome, and centromere-proximal crossovers are associated with an increased risk of aneuploidy, including Trisomy 21 in humans. Here, we identify the conserved Ctf19/CCAN kinetochore sub-complex as a major factor that minimizes potentially deleterious centromere-proximal crossovers in budding yeast. We uncover multi-layered suppression of pericentromeric recombination by the Ctf19 complex, operating across distinct chromosomal distances. The Ctf19 complex prevents meiotic DNA break formation, the initiating event of recombination, proximal to the centromere. The Ctf19 complex independently drives the enrichment of cohesin throughout the broader pericentromere to suppress crossovers, but not DNA breaks. This non-canonical role of the kinetochore in defining a chromosome domain that is refractory to crossovers adds a new layer of functionality by which the kinetochore prevents the incidence of chromosome segregation errors that generate aneuploid gametes.
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Affiliation(s)
- Nadine Vincenten
- The Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Lisa-Marie Kuhl
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Isabel Lam
- Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Ashwini Oke
- Department of Obstetrics, Gynecology and Reproductive Sciences, Center of Reproductive Sciences, University of California, San Francisco, San Francisco, United States
| | - Alastair Rw Kerr
- The Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | | | - Jennifer Fung
- Department of Obstetrics, Gynecology and Reproductive Sciences, Center of Reproductive Sciences, University of California, San Francisco, San Francisco, United States
| | - Scott Keeney
- Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Gerben Vader
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Adèle L Marston
- The Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
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Endres L, Dedon PC, Begley TJ. Codon-biased translation can be regulated by wobble-base tRNA modification systems during cellular stress responses. RNA Biol 2015; 12:603-14. [PMID: 25892531 DOI: 10.1080/15476286.2015.1031947] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
tRNA (tRNA) is a key molecule used for protein synthesis, with multiple points of stress-induced regulation that can include transcription, transcript processing, localization and ribonucleoside base modification. Enzyme-catalyzed modification of tRNA occurs at a number of base and sugar positions and has the potential to influence specific anticodon-codon interactions and regulate translation. Notably, altered tRNA modification has been linked to mitochondrial diseases and cancer progression. In this review, specific to Eukaryotic systems, we discuss how recent systems-level analyses using a bioanalytical platform have revealed that there is extensive reprogramming of tRNA modifications in response to cellular stress and during cell cycle progression. Combined with genome-wide codon bias analytics and gene expression studies, a model emerges in which stress-induced reprogramming of tRNA drives the translational regulation of critical response proteins whose transcripts display a distinct codon bias. Termed Modification Tunable Transcripts (MoTTs), (1) we define them as (1) transcripts that use specific degenerate codons and codon biases to encode critical stress response proteins, and (2) transcripts whose translation is influenced by changes in wobble base tRNA modification. In this review we note that the MoTTs translational model is also applicable to the process of stop-codon recoding for selenocysteine incorporation, as stop-codon recoding involves a selective codon bias and modified tRNA to decode selenocysteine during the translation of a key subset of oxidative stress response proteins. Further, we discuss how in addition to RNA modification analytics, the comprehensive characterization of translational regulation of specific transcripts requires a variety of tools, including high coverage codon-reporters, ribosome profiling and linked genomic and proteomic approaches. Together these tools will yield important new insights into the role of translational elongation in cell stress response.
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Affiliation(s)
- Lauren Endres
- a College of Nanoscale Science and Engineering; State University of New York ; Albany , NY USA
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Protein Composition of Infectious Spores Reveals Novel Sexual Development and Germination Factors in Cryptococcus. PLoS Genet 2015; 11:e1005490. [PMID: 26313153 PMCID: PMC4551743 DOI: 10.1371/journal.pgen.1005490] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 08/07/2015] [Indexed: 11/19/2022] Open
Abstract
Spores are an essential cell type required for long-term survival across diverse organisms in the tree of life and are a hallmark of fungal reproduction, persistence, and dispersal. Among human fungal pathogens, spores are presumed infectious particles, but relatively little is known about this robust cell type. Here we used the meningitis-causing fungus Cryptococcus neoformans to determine the roles of spore-resident proteins in spore biology. Using highly sensitive nanoscale liquid chromatography/mass spectrometry, we compared the proteomes of spores and vegetative cells (yeast) and identified eighteen proteins specifically enriched in spores. The genes encoding these proteins were deleted, and the resulting strains were evaluated for discernable phenotypes. We hypothesized that spore-enriched proteins would be preferentially involved in spore-specific processes such as dormancy, stress resistance, and germination. Surprisingly, however, the majority of the mutants harbored defects in sexual development, the process by which spores are formed. One mutant in the cohort was defective in the spore-specific process of germination, showing a delay specifically in the initiation of vegetative growth. Thus, by using this in-depth proteomics approach as a screening tool for cell type-specific proteins and combining it with molecular genetics, we successfully identified the first germination factor in C. neoformans. We also identified numerous proteins with previously unknown functions in both sexual development and spore composition. Our findings provide the first insights into the basic protein components of infectious spores and reveal unexpected molecular connections between infectious particle production and spore composition in a pathogenic eukaryote.
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Meyer RE, Chuong HH, Hild M, Hansen CL, Kinter M, Dawson DS. Ipl1/Aurora-B is necessary for kinetochore restructuring in meiosis I in Saccharomyces cerevisiae. Mol Biol Cell 2015; 26:2986-3000. [PMID: 26157162 PMCID: PMC4551314 DOI: 10.1091/mbc.e15-01-0032] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 06/30/2015] [Indexed: 11/11/2022] Open
Abstract
In mitosis, the centromeres of sister chromosomes are pulled toward opposite poles of the spindle. In meiosis I, the opposite is true: the sister centromeres move together to the same pole, and the homologous chromosomes are pulled apart. This change in segregation patterns demands that between the final mitosis preceding meiosis and the first meiotic division, the kinetochores must be restructured. In budding yeast, unlike mammals, kinetochores are largely stable throughout the mitotic cycle. In contrast, previous work with budding and fission yeast showed that some outer kinetochore proteins are lost in early meiosis. We use quantitative mass spectrometry methods and imaging approaches to explore the kinetochore restructuring process that occurs in meiosis I in budding yeast. The Ndc80 outer kinetochore complex, but not other subcomplexes, is shed upon meiotic entry. This shedding is regulated by the conserved protein kinase Ipl1/Aurora-B and promotes the subsequent assembly of a kinetochore that will confer meiosis-specific segregation patterns on the chromosome.
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Affiliation(s)
- Régis E Meyer
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Hoa H Chuong
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Marrett Hild
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Christina L Hansen
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Michael Kinter
- Program in Free Radical Biology and Aging, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Dean S Dawson
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104 Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
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59
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Eaf1p Is Required for Recruitment of NuA4 in Targeting TFIID to the Promoters of the Ribosomal Protein Genes for Transcriptional Initiation In Vivo. Mol Cell Biol 2015; 35:2947-64. [PMID: 26100014 DOI: 10.1128/mcb.01524-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 05/24/2015] [Indexed: 01/13/2023] Open
Abstract
NuA4 (nucleosome acetyltransferase of H4) promotes transcriptional initiation of TFIID (a complex of TBP and TBP-associated factors [TAFs])-dependent ribosomal protein genes involved in ribosome biogenesis. However, it is not clearly understood how NuA4 regulates the transcription of ribosomal protein genes. Here, we show that NuA4 is recruited to the promoters of ribosomal protein genes, such as RPS5, RPL2B, and RPS11B, for TFIID recruitment to initiate transcription, and the recruitment of NuA4 to these promoters is impaired in the absence of its Eaf1p component. Intriguingly, impaired NuA4 recruitment in a Δeaf1 strain depletes recruitment of TFIID (a TAF-dependent form of TBP) but not the TAF-independent form of TBP to the promoters of ribosomal protein genes. However, in the absence of NuA4, SAGA (Spt-Ada-Gcn5-acetyltransferase) is involved in targeting the TAF-independent form of TBP to the promoters of ribosomal protein genes for transcriptional initiation. Thus, NuA4 plays an important role in targeting TFIID to the promoters of ribosomal protein genes for transcriptional initiation in vivo. Such a function is mediated via its targeted histone acetyltransferase activity. In the absence of NuA4, ribosomal protein genes lose TFIID dependency and become SAGA dependent for transcriptional initiation. Collectively, these results provide significant insights into the regulation of ribosomal protein gene expression and, hence, ribosome biogenesis and functions.
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60
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Voets E, Wolthuis R. MASTL promotes cyclin B1 destruction by enforcing Cdc20-independent binding of cyclin B1 to the APC/C. Biol Open 2015; 4:484-95. [PMID: 25750436 PMCID: PMC4400591 DOI: 10.1242/bio.201410793] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When cells enter mitosis, the anaphase-promoting complex/cyclosome (APC/C) is activated by phosphorylation and binding of Cdc20. The RXXL destruction box (D-box) of cyclin B1 only binds Cdc20 after release of the spindle checkpoint in metaphase, initiating cyclin B1 ubiquitination upon chromosome bi-orientation. However, we found that cyclin B1, through Cdk1 and Cks, is targeted to the phosphorylated APC/CCdc20 at the start of prometaphase, when the spindle checkpoint is still active. Here, we show that MASTL is essential for cyclin B1 recruitment to the mitotic APC/C and that this occurs entirely independently of Cdc20. Importantly, MASTL-directed binding of cyclin B1 to spindle checkpoint-inhibited APC/CCdc20 critically supports efficient cyclin B1 destruction after checkpoint release. A high incidence of anaphase bridges observed in response to MASTL RNAi may result from cyclin B1 remaining after securin destruction, which is insufficient to keep MASTL-depleted cells in mitosis but delays the activation of separase.
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Affiliation(s)
- Erik Voets
- Division of Cell Biology I (B5) and Division of Molecular Carcinogenesis (B7), The Netherlands Cancer Institute (NKI-AvL), Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Rob Wolthuis
- Division of Cell Biology I (B5) and Division of Molecular Carcinogenesis (B7), The Netherlands Cancer Institute (NKI-AvL), Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands Section of Oncogenetics, Department of Clinical Genetics and CCA/V-ICI Research Program Oncogenesis, VUmc Medical Faculty, van de Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
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61
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Abstract
During eukaryotic cell division, chromosomes must be precisely partitioned to daughter cells. This relies on a mechanism to move chromosomes in defined directions within the parental cell. While sister chromatids are segregated from one another in mitosis and meiosis II, specific adaptations enable the segregation of homologous chromosomes during meiosis I to reduce ploidy for gamete production. Many of the factors that drive these directed chromosome movements are known, and their molecular mechanism has started to be uncovered. Here we review the mechanisms of eukaryotic chromosome segregation, with a particular emphasis on the modifications that ensure the segregation of homologous chromosomes during meiosis I.
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Affiliation(s)
- Eris Duro
- The Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Adèle L Marston
- The Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
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62
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Kim J, Ishiguro KI, Nambu A, Akiyoshi B, Yokobayashi S, Kagami A, Ishiguro T, Pendas AM, Takeda N, Sakakibara Y, Kitajima TS, Tanno Y, Sakuno T, Watanabe Y. Meikin is a conserved regulator of meiosis-I-specific kinetochore function. Nature 2015; 517:466-71. [PMID: 25533956 DOI: 10.1038/nature14097] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/19/2014] [Indexed: 12/11/2022]
Abstract
The kinetochore is the crucial apparatus regulating chromosome segregation in mitosis and meiosis. Particularly in meiosis I, unlike in mitosis, sister kinetochores are captured by microtubules emanating from the same spindle pole (mono-orientation) and centromeric cohesion mediated by cohesin is protected in the following anaphase. Although meiotic kinetochore factors have been identified only in budding and fission yeasts, these molecules and their functions are thought to have diverged earlier. Therefore, a conserved mechanism for meiotic kinetochore regulation remains elusive. Here we have identified in mouse a meiosis-specific kinetochore factor that we termed MEIKIN, which functions in meiosis I but not in meiosis II or mitosis. MEIKIN plays a crucial role in both mono-orientation and centromeric cohesion protection, partly by stabilizing the localization of the cohesin protector shugoshin. These functions are mediated mainly by the activity of Polo-like kinase PLK1, which is enriched to kinetochores in a MEIKIN-dependent manner. Our integrative analysis indicates that the long-awaited key regulator of meiotic kinetochore function is Meikin, which is conserved from yeasts to humans.
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Affiliation(s)
- Jihye Kim
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Kei-ichiro Ishiguro
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Aya Nambu
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Bungo Akiyoshi
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Shihori Yokobayashi
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Ayano Kagami
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Tadashi Ishiguro
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Alberto M Pendas
- Instituto de Biología Molecular y Celular del Cáncer (CSIC-USAL), 37007 Salamanca, Spain
| | - Naoki Takeda
- Center for Animal Resources and Development, Kumamoto University, 2-2-1 Honjo, Kumamoto 860-0811 Japan
| | - Yogo Sakakibara
- Laboratory for Chromosome Segregation, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Tomoya S Kitajima
- Laboratory for Chromosome Segregation, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Yuji Tanno
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Takeshi Sakuno
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Yoshinori Watanabe
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
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63
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Abstract
The shugoshin/Mei-S332 family are proteins that associate with the chromosomal region surrounding the centromere (the pericentromere) and that play multiple and distinct roles in ensuring the accuracy of chromosome segregation during both mitosis and meiosis. The underlying role of shugoshins appears to be to serve as pericentromeric adaptor proteins that recruit several different effectors to this region of the chromosome to regulate processes critical for chromosome segregation. Crucially, shugoshins undergo changes in their localization in response to the tension that is exerted on sister chromosomes by the forces of the spindle that will pull them apart. This has led to the idea that shugoshins provide a platform for activities required at the pericentromere only when sister chromosomes lack tension. Conversely, disassembly of the shugoshin pericentromeric platform may provide a signal that sister chromosomes are under tension. Here the functions and regulation of these important tension-sensitive pericentromeric proteins are discussed.
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64
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Eshleman HD, Morgan DO. Sgo1 recruits PP2A to chromosomes to ensure sister chromatid bi-orientation during mitosis. J Cell Sci 2014; 127:4974-83. [PMID: 25236599 DOI: 10.1242/jcs.161273] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Sister chromatid bi-orientation on the mitotic spindle is essential for proper chromosome segregation. Defects in bi-orientation are sensed and corrected to prevent chromosome mis-segregation and aneuploidy. This response depends on the adaptor protein Sgo1, which associates with pericentromeric chromatin in mitosis. The mechanisms underlying Sgo1 function and regulation are unclear. Here, we show that Sgo1 is an anaphase-promoting complex/cyclosome (APC/C) substrate in budding yeast (Saccharomyces cerevisiae), and that its mitotic destruction depends on an unusual D-box-related sequence motif near its C-terminus. We find that the removal of Sgo1 from chromosomes before anaphase is not dependent on its destruction, but rather on other mechanisms responsive to tension between sister chromatids. Additionally, we find that Sgo1 recruits the protein phosphatase 2A (PP2A) isoform containing Rts1 to the pericentromeric region prior to bi-orientation, and that artificial recruitment of Rts1 to this region of a single chromosome is sufficient to perform the function of Sgo1 on that chromosome. We conclude that in early mitosis, Sgo1 associates transiently with pericentromeric chromatin to promote bi-orientation, in large part by recruiting the Rts1 isoform of PP2A.
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Affiliation(s)
- Heather D Eshleman
- Departments of Physiology and Biochemistry and Biophysics, University of California, San Francisco, CA 94158, USA
| | - David O Morgan
- Departments of Physiology and Biochemistry and Biophysics, University of California, San Francisco, CA 94158, USA
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Hurtado S, Kim Guisbert KS, Sontheimer EJ. SPO24 is a transcriptionally dynamic, small ORF-encoding locus required for efficient sporulation in Saccharomyces cerevisiae. PLoS One 2014; 9:e105058. [PMID: 25127041 PMCID: PMC4134269 DOI: 10.1371/journal.pone.0105058] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Accepted: 07/20/2014] [Indexed: 01/22/2023] Open
Abstract
In Saccharomyces cerevisiae, meiosis and sporulation are highly regulated responses that are driven in part by changes in RNA expression. Alternative mRNA forms with extended 5′ UTRs are atypical in S. cerevisiae, and 5′ extensions with upstream open reading frames (uORFs) are even more unusual. Here we characterize the gene YPR036W-A, now renamed SPO24, which encodes a very small (67-amino-acid) protein. This gene gives rise to two mRNA forms: a shorter form throughout meiosis and a longer, 5′-extended form in mid-late meiosis. The latter form includes a uORF for a 14-amino-acid peptide (Spo24u14). Deletion of the downstream ORF (dORF) leads to sporulation defects and the appearance of pseudohyphae-like projections. Experiments with luciferase reporters indicate that the uORF does not downregulate dORF translation. The protein encoded by the dORF (Spo24d67) localizes to the prospore membrane and is differentially phosphorylated during meiosis. Transcription of the 5′-extended mRNA in mid-meiosis depends upon the presence of two middle sporulation elements (MSEs). Removal of the MSEs severely inhibits the mid-meiotic appearance of the 5′-extended mRNA and limits the ability of plasmid-borne SPO24 to rescue the sporulation defect of a spo24Δ mutant, suggesting that the 5′-extended mRNA is functionally important. These results reveal Spo24d67 as a sporulation-related factor that is encoded by a transcriptionally dynamic, uORF-containing locus.
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Affiliation(s)
- Sara Hurtado
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Karen S. Kim Guisbert
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Erik J. Sontheimer
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
- * E-mail:
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66
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Sau S, Conrad MN, Lee CY, Kaback DB, Dresser ME, Jayaram M. A selfish DNA element engages a meiosis-specific motor and telomeres for germ-line propagation. ACTA ACUST UNITED AC 2014; 205:643-61. [PMID: 24914236 PMCID: PMC4050733 DOI: 10.1083/jcb.201312002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The yeast 2 micron plasmid engages a meiosis-specific motor that orchestrates telomere-led chromosome movements for its telomere-associated segregation during meiosis I. The chromosome-like mitotic stability of the yeast 2 micron plasmid is conferred by the plasmid proteins Rep1-Rep2 and the cis-acting locus STB, likely by promoting plasmid-chromosome association and segregation by hitchhiking. Our analysis reveals that stable plasmid segregation during meiosis requires the bouquet proteins Ndj1 and Csm4. Plasmid relocalization from the nuclear interior in mitotic cells to the periphery at or proximal to telomeres rises from early meiosis to pachytene. Analogous to chromosomes, the plasmid undergoes Csm4- and Ndj1-dependent rapid prophase movements with speeds comparable to those of telomeres. Lack of Ndj1 partially disrupts plasmid–telomere association without affecting plasmid colocalization with the telomere-binding protein Rap1. The plasmid appears to engage a meiosis-specific motor that orchestrates telomere-led chromosome movements for its telomere-associated segregation during meiosis I. This hitherto uncharacterized mode of germ-line transmission by a selfish genetic element signifies a mechanistic variation within the shared theme of chromosome-coupled plasmid segregation during mitosis and meiosis.
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Affiliation(s)
- Soumitra Sau
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712
| | - Michael N Conrad
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Chih-Ying Lee
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - David B Kaback
- Department of Microbiology and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ 07101
| | - Michael E Dresser
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Makkuni Jayaram
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712
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67
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Nerusheva OO, Galander S, Fernius J, Kelly D, Marston AL. Tension-dependent removal of pericentromeric shugoshin is an indicator of sister chromosome biorientation. Genes Dev 2014; 28:1291-309. [PMID: 24939933 PMCID: PMC4066400 DOI: 10.1101/gad.240291.114] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 05/20/2014] [Indexed: 12/24/2022]
Abstract
During mitosis and meiosis, sister chromatid cohesion resists the pulling forces of microtubules, enabling the generation of tension at kinetochores upon chromosome biorientation. How tension is read to signal the bioriented state remains unclear. Shugoshins form a pericentromeric platform that integrates multiple functions to ensure proper chromosome biorientation. Here we show that budding yeast shugoshin Sgo1 dissociates from the pericentromere reversibly in response to tension. The antagonistic activities of the kinetochore-associated Bub1 kinase and the Sgo1-bound phosphatase protein phosphatase 2A (PP2A)-Rts1 underlie a tension-dependent circuitry that enables Sgo1 removal upon sister kinetochore biorientation. Sgo1 dissociation from the pericentromere triggers dissociation of condensin and Aurora B from the centromere, thereby stabilizing the bioriented state. Conversely, forcing sister kinetochores to be under tension during meiosis I leads to premature Sgo1 removal and precocious loss of pericentromeric cohesion. Overall, we show that the pivotal role of shugoshin is to build a platform at the pericentromere that attracts activities that respond to the absence of tension between sister kinetochores. Disassembly of this platform in response to intersister kinetochore tension signals the bioriented state. Therefore, tension sensing by shugoshin is a central mechanism by which the bioriented state is read.
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Affiliation(s)
- Olga O. Nerusheva
- The Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
| | - Stefan Galander
- The Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
| | - Josefin Fernius
- The Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
| | - David Kelly
- The Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
| | - Adele L. Marston
- The Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
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68
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Rossetto D, Cramet M, Wang AY, Steunou AL, Lacoste N, Schulze JM, Côté V, Monnet-Saksouk J, Piquet S, Nourani A, Kobor MS, Côté J. Eaf5/7/3 form a functionally independent NuA4 submodule linked to RNA polymerase II-coupled nucleosome recycling. EMBO J 2014; 33:1397-415. [PMID: 24843044 DOI: 10.15252/embj.201386433] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The NuA4 histone acetyltransferase complex is required for gene regulation, cell cycle progression, and DNA repair. Dissection of the 13-subunit complex reveals that the Eaf7 subunit bridges Eaf5 with Eaf3, a H3K36me3-binding chromodomain protein, and this Eaf5/7/3 trimer is anchored to NuA4 through Eaf5. This trimeric subcomplex represents a functional module, and a large portion exists in a native form outside the NuA4 complex. Gene-specific and genome-wide location analyses indicate that Eaf5/7/3 correlates with transcription activity and is enriched over the coding region. In agreement with a role in transcription elongation, the Eaf5/7/3 trimer interacts with phosphorylated RNA polymerase II and helps its progression. Loss of Eaf5/7/3 partially suppresses intragenic cryptic transcription arising in set2 mutants, supporting a role in nucleosome destabilization. On the other hand, loss of the trimer leads to an increase of replication-independent histone exchange over the coding region of transcribed genes. Taken together, these results lead to a model where Eaf5/7/3 associates with elongating polymerase to promote the disruption of nucleosomes in its path, but also their refolding in its wake.
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Affiliation(s)
- Dorine Rossetto
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center Centre de Recherche du CHU de Québec-Axe Oncologie Hôtel-Dieu de Québec, Quebec City, QC, Canada
| | - Myriam Cramet
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center Centre de Recherche du CHU de Québec-Axe Oncologie Hôtel-Dieu de Québec, Quebec City, QC, Canada
| | - Alice Y Wang
- Center for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, BC, Canada
| | - Anne-Lise Steunou
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center Centre de Recherche du CHU de Québec-Axe Oncologie Hôtel-Dieu de Québec, Quebec City, QC, Canada
| | - Nicolas Lacoste
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center Centre de Recherche du CHU de Québec-Axe Oncologie Hôtel-Dieu de Québec, Quebec City, QC, Canada
| | - Julia M Schulze
- Center for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, BC, Canada
| | - Valérie Côté
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center Centre de Recherche du CHU de Québec-Axe Oncologie Hôtel-Dieu de Québec, Quebec City, QC, Canada
| | - Julie Monnet-Saksouk
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center Centre de Recherche du CHU de Québec-Axe Oncologie Hôtel-Dieu de Québec, Quebec City, QC, Canada
| | - Sandra Piquet
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center Centre de Recherche du CHU de Québec-Axe Oncologie Hôtel-Dieu de Québec, Quebec City, QC, Canada
| | - Amine Nourani
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center Centre de Recherche du CHU de Québec-Axe Oncologie Hôtel-Dieu de Québec, Quebec City, QC, Canada
| | - Michael S Kobor
- Center for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, BC, Canada
| | - Jacques Côté
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center Centre de Recherche du CHU de Québec-Axe Oncologie Hôtel-Dieu de Québec, Quebec City, QC, Canada
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69
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A genome-wide screen for sporulation-defective mutants in Schizosaccharomyces pombe. G3-GENES GENOMES GENETICS 2014; 4:1173-82. [PMID: 24727291 PMCID: PMC4065261 DOI: 10.1534/g3.114.011049] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Yeast sporulation is a highly regulated developmental program by which diploid cells generate haploid gametes, termed spores. To better define the genetic pathways regulating sporulation, a systematic screen of the set of ~3300 nonessential Schizosaccharomyces pombe gene deletion mutants was performed to identify genes required for spore formation. A high-throughput genetic method was used to introduce each mutant into an h(90) background, and iodine staining was used to identify sporulation-defective mutants. The screen identified 34 genes whose deletion reduces sporulation, including 15 that are defective in forespore membrane morphogenesis. In S. pombe, the total number of sporulation-defective mutants is a significantly smaller fraction of coding genes than in S. cerevisiae, which reflects the different evolutionary histories and biology of the two yeasts.
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70
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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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71
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Verzijlbergen KF, Nerusheva OO, Kelly D, Kerr A, Clift D, de Lima Alves F, Rappsilber J, Marston AL. Shugoshin biases chromosomes for biorientation through condensin recruitment to the pericentromere. eLife 2014; 3:e01374. [PMID: 24497542 PMCID: PMC3910079 DOI: 10.7554/elife.01374] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
To protect against aneuploidy, chromosomes must attach to microtubules from opposite poles (‘biorientation’) prior to their segregation during mitosis. Biorientation relies on the correction of erroneous attachments by the aurora B kinase, which destabilizes kinetochore-microtubule attachments that lack tension. Incorrect attachments are also avoided because sister kinetochores are intrinsically biased towards capture by microtubules from opposite poles. Here, we show that shugoshin acts as a pericentromeric adaptor that plays dual roles in biorientation in budding yeast. Shugoshin maintains the aurora B kinase at kinetochores that lack tension, thereby engaging the error correction machinery. Shugoshin also recruits the chromosome-organizing complex, condensin, to the pericentromere. Pericentromeric condensin biases sister kinetochores towards capture by microtubules from opposite poles. Our findings uncover the molecular basis of the bias to sister kinetochore capture and expose shugoshin as a pericentromeric hub controlling chromosome biorientation. DOI:http://dx.doi.org/10.7554/eLife.01374.001 When a cell divides to create two new daughter cells, it must produce a copy of each of its chromosomes. It is important that each daughter cell gets just one copy of each chromosome. If an error occurs and one cell gets two copies of a single chromosome, it can lead to cancer or birth defects. Fortunately, there are multiple checks to ensure that this does not happen. During cell division the chromosomes line up in a way that increases the likelihood that each daughter cell will have one copy of each chromosome. After this process—which is called biorientation—is completed, microtubules pull the chromosomes to opposite ends of the cell, which then divides. Proteins called shugoshin proteins are known to be involved in biorientation in many organisms. These proteins are found in a region called the pericentromere, which surrounds the area on the chromosomes that the microtubules attach to, but the details of their involvement in biorientation are not fully understood. Now Verzijlbergen et al. have exploited sophisticated genetic techniques in yeast to explore how shugoshin proteins work. These experiments showed that the shugoshin protein helps to recruit condensin—a protein that keeps the DNA organized within the chromosome—to the pericentromere to assist with biorientation. It also keeps aurora B kinase—one of the enzymes that helps to correct errors during cell division—in the pericentromere when a microtubule attaches to the wrong chromosome. These results help us understand how a ‘hub’ in the pericentromere ensures biorientation. The next challenge will be to understand how this hub is disassembled after biorientation to allow error-free cell division to proceed. As shugoshins have been found to be damaged in some cancers, understanding the workings of this hub could also shed new light on how they contribute to disease. DOI:http://dx.doi.org/10.7554/eLife.01374.002
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Affiliation(s)
- Kitty F Verzijlbergen
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
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72
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Marston AL. Chromosome segregation in budding yeast: sister chromatid cohesion and related mechanisms. Genetics 2014; 196:31-63. [PMID: 24395824 PMCID: PMC3872193 DOI: 10.1534/genetics.112.145144] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 09/18/2013] [Indexed: 12/28/2022] Open
Abstract
Studies on budding yeast have exposed the highly conserved mechanisms by which duplicated chromosomes are evenly distributed to daughter cells at the metaphase-anaphase transition. The establishment of proteinaceous bridges between sister chromatids, a function provided by a ring-shaped complex known as cohesin, is central to accurate segregation. It is the destruction of this cohesin that triggers the segregation of chromosomes following their proper attachment to microtubules. Since it is irreversible, this process must be tightly controlled and driven to completion. Furthermore, during meiosis, modifications must be put in place to allow the segregation of maternal and paternal chromosomes in the first division for gamete formation. Here, I review the pioneering work from budding yeast that has led to a molecular understanding of the establishment and destruction of cohesion.
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Affiliation(s)
- Adele L Marston
- The Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
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73
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Montefusco DJ, Matmati N, Hannun YA. The yeast sphingolipid signaling landscape. Chem Phys Lipids 2014; 177:26-40. [PMID: 24220500 PMCID: PMC4211598 DOI: 10.1016/j.chemphyslip.2013.10.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/18/2013] [Accepted: 10/19/2013] [Indexed: 12/13/2022]
Abstract
Sphingolipids are recognized as signaling mediators in a growing number of pathways, and represent potential targets to address many diseases. The study of sphingolipid signaling in yeast has created a number of breakthroughs in the field, and has the potential to lead future advances. The aim of this article is to provide an inclusive view of two major frontiers in yeast sphingolipid signaling. In the first section, several key studies in the field of sphingolipidomics are consolidated to create a yeast sphingolipidome that ranks nearly all known sphingolipid species by their level in a resting yeast cell. The second section presents an overview of most known phenotypes identified for sphingolipid gene mutants, presented with the intention of illuminating not yet discovered connections outside and inside of the field.
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Affiliation(s)
- David J Montefusco
- Dept. Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, United States.
| | - Nabil Matmati
- Stony Brook Cancer Center, Stony Brook University, Stony Brook, NY, United States
| | - Yusuf A Hannun
- Stony Brook Cancer Center, Stony Brook University, Stony Brook, NY, United States.
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74
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Abstract
Mitosis and meiosis are essential processes that occur during development. Throughout these processes, cohesion is required to keep the sister chromatids together until their separation at anaphase. Cohesion is created by multiprotein subunit complexes called cohesins. Although the subunits differ slightly in mitosis and meiosis, the canonical cohesin complex is composed of four subunits that are quite diverse. The cohesin complexes are also important for DNA repair, gene expression, development, and genome integrity. Here we provide an overview of the roles of cohesins during these different events as well as their roles in human health and disease, including the cohesinopathies. Although the exact roles and mechanisms of these proteins are still being elucidated, this review serves as a guide for the current knowledge of cohesins.
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Affiliation(s)
- Amanda S Brooker
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, 245 N. 15th Street, MS 497, Philadelphia, PA, 19102, USA
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75
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Copsey A, Tang S, Jordan PW, Blitzblau HG, Newcombe S, Chan ACH, Newnham L, Li Z, Gray S, Herbert AD, Arumugam P, Hochwagen A, Hunter N, Hoffmann E. Smc5/6 coordinates formation and resolution of joint molecules with chromosome morphology to ensure meiotic divisions. PLoS Genet 2013; 9:e1004071. [PMID: 24385939 PMCID: PMC3873251 DOI: 10.1371/journal.pgen.1004071] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 11/08/2013] [Indexed: 11/22/2022] Open
Abstract
During meiosis, Structural Maintenance of Chromosome (SMC) complexes underpin two fundamental features of meiosis: homologous recombination and chromosome segregation. While meiotic functions of the cohesin and condensin complexes have been delineated, the role of the third SMC complex, Smc5/6, remains enigmatic. Here we identify specific, essential meiotic functions for the Smc5/6 complex in homologous recombination and the regulation of cohesin. We show that Smc5/6 is enriched at centromeres and cohesin-association sites where it regulates sister-chromatid cohesion and the timely removal of cohesin from chromosomal arms, respectively. Smc5/6 also localizes to recombination hotspots, where it promotes normal formation and resolution of a subset of joint-molecule intermediates. In this regard, Smc5/6 functions independently of the major crossover pathway defined by the MutLγ complex. Furthermore, we show that Smc5/6 is required for stable chromosomal localization of the XPF-family endonuclease, Mus81-Mms4(Eme1). Our data suggest that the Smc5/6 complex is required for specific recombination and chromosomal processes throughout meiosis and that in its absence, attempts at cell division with unresolved joint molecules and residual cohesin lead to severe recombination-induced meiotic catastrophe.
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Affiliation(s)
- Alice Copsey
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Shangming Tang
- Howard Hughes Medical Institute, University of California, Davis, Davis, California, United States of America
- Department of Microbiology & Molecular Genetics, University of California, Davis, Davis, California, United States of America
| | - Philip W. Jordan
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Hannah G. Blitzblau
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Sonya Newcombe
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Andrew Chi-ho Chan
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Louise Newnham
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Zhaobo Li
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Stephen Gray
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Alex D. Herbert
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Prakash Arumugam
- Department of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Andreas Hochwagen
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
- Department of Biology, New York University, New York, New York, United States of America
| | - Neil Hunter
- Howard Hughes Medical Institute, University of California, Davis, Davis, California, United States of America
- Department of Microbiology & Molecular Genetics, University of California, Davis, Davis, California, United States of America
- Department of Biology, New York University, New York, New York, United States of America
- Department of Molecular & Cellular Biology, University of California, Davis, Davis, California, United States of America
- Department of Cell Biology & Human Anatomy, University of California, Davis, Davis, California, United States of America
| | - Eva Hoffmann
- MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
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76
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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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77
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Hinshaw SM, Harrison SC. An Iml3-Chl4 heterodimer links the core centromere to factors required for accurate chromosome segregation. Cell Rep 2013; 5:29-36. [PMID: 24075991 PMCID: PMC3888643 DOI: 10.1016/j.celrep.2013.08.036] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 07/21/2013] [Accepted: 08/16/2013] [Indexed: 01/12/2023] Open
Abstract
Accurate segregation of genetic material in eukaryotes relies on the kinetochore, a multiprotein complex that connects centromeric DNA with microtubules. In yeast and humans, two proteins-Mif2/CENP-C and Chl4/CNEP-N-interact with specialized centromeric nucleosomes and establish distinct but cross-connecting axes of chromatin-microtubule linkage. Proteins recruited by Chl4/CENP-N include a subset that regulates chromosome transmission fidelity. We show that Chl4 and a conserved member of this subset, Iml3, both from Saccharomyces cerevisiae, form a stable protein complex that interacts with Mif2 and Sgo1. We have determined the structures of an Iml3 homodimer and an Iml3-Chl4 heterodimer, which suggest a mechanism for regulating the assembly of this functional axis of the kinetochore. We propose that at the core centromere, the Chl4-Iml3 complex participates in recruiting factors, such as Sgo1, that influence sister chromatid cohesion and encourage sister kinetochore biorientation.
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Affiliation(s)
- Stephen M Hinshaw
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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78
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Peraza-Reyes L, Berteaux-Lecellier V. Peroxisomes and sexual development in fungi. Front Physiol 2013; 4:244. [PMID: 24046747 PMCID: PMC3764329 DOI: 10.3389/fphys.2013.00244] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 08/19/2013] [Indexed: 11/13/2022] Open
Abstract
Peroxisomes are versatile and dynamic organelles that are essential for the development of most eukaryotic organisms. In fungi, many developmental processes, such as sexual development, require the activity of peroxisomes. Sexual reproduction in fungi involves the formation of meiotic-derived sexual spores, often takes place inside multicellular fruiting bodies and requires precise coordination between the differentiation of multiple cell types and the progression of karyogamy and meiosis. Different peroxisomal functions contribute to the orchestration of this complex developmental process. Peroxisomes are required to sustain the formation of fruiting bodies and the maturation and germination of sexual spores. They facilitate the mobilization of reserve compounds via fatty acid β-oxidation and the glyoxylate cycle, allowing the generation of energy and biosynthetic precursors. Additionally, peroxisomes are implicated in the progression of meiotic development. During meiotic development in Podospora anserina, there is a precise modulation of peroxisome assembly and dynamics. This modulation includes changes in peroxisome size, number and localization, and involves a differential activity of the protein-machinery that drives the import of proteins into peroxisomes. Furthermore, karyogamy, entry into meiosis and sorting of meiotic-derived nuclei into sexual spores all require the activity of peroxisomes. These processes rely on different peroxisomal functions and likely depend on different pathways for peroxisome assembly. Indeed, emerging studies support the existence of distinct import channels for peroxisomal proteins that contribute to different developmental stages.
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Affiliation(s)
- Leonardo Peraza-Reyes
- CNRS, Institut de Génétique et Microbiologie, University Paris-Sud, UMR8621 Orsay, France
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79
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Lin CPC, Kim C, Smith SO, Neiman AM. A highly redundant gene network controls assembly of the outer spore wall in S. cerevisiae. PLoS Genet 2013; 9:e1003700. [PMID: 23966878 PMCID: PMC3744438 DOI: 10.1371/journal.pgen.1003700] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 06/20/2013] [Indexed: 12/01/2022] Open
Abstract
The spore wall of Saccharomyces cerevisiae is a multilaminar extracellular structure that is formed de novo in the course of sporulation. The outer layers of the spore wall provide spores with resistance to a wide variety of environmental stresses. The major components of the outer spore wall are the polysaccharide chitosan and a polymer formed from the di-amino acid dityrosine. Though the synthesis and export pathways for dityrosine have been described, genes directly involved in dityrosine polymerization and incorporation into the spore wall have not been identified. A synthetic gene array approach to identify new genes involved in outer spore wall synthesis revealed an interconnected network influencing dityrosine assembly. This network is highly redundant both for genes of different activities that compensate for the loss of each other and for related genes of overlapping activity. Several of the genes in this network have paralogs in the yeast genome and deletion of entire paralog sets is sufficient to severely reduce dityrosine fluorescence. Solid-state NMR analysis of partially purified outer spore walls identifies a novel component in spore walls from wild type that is absent in some of the paralog set mutants. Localization of gene products identified in the screen reveals an unexpected role for lipid droplets in outer spore wall formation. The cell wall of fungi is a complex extracellular matrix and an important target for antifungal drugs. Assembly of the wall during spore formation in baker's yeast is a useful model for fungal wall development. The outermost layers of the spore wall are composed of a polymer of dityrosine connected to an underlying polysaccharide layer. The assembly pathway of this dityrosine polymer is not known. Using a genetic approach we reveal a network of genes that function redundantly to control dityrosine layer synthesis. Solid state NMR analysis of spore walls from wild-type and mutant cells reveals a novel constituent of the spore wall that may link the dityrosine to the underlying polysaccharides and a role for lipid droplets in the incorporation of this new component into the spore wall.
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Affiliation(s)
- Coney Pei-Chen Lin
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Carey Kim
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Steven O. Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Aaron M. Neiman
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
- * E-mail:
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80
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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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81
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The Mub1/Ubr2 ubiquitin ligase complex regulates the conserved Dsn1 kinetochore protein. PLoS Genet 2013; 9:e1003216. [PMID: 23408894 PMCID: PMC3567142 DOI: 10.1371/journal.pgen.1003216] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Accepted: 11/19/2012] [Indexed: 01/17/2023] Open
Abstract
The kinetochore is the macromolecular complex that assembles onto centromeric DNA and orchestrates the segregation of duplicated chromosomes. More than 60 components make up the budding yeast kinetochore, including inner kinetochore proteins that bind to centromeric chromatin and outer proteins that directly interact with microtubules. However, little is known about how these components assemble into a functional kinetochore and whether there are quality control mechanisms that monitor kinetochore integrity. We previously developed a method to isolate kinetochore particles via purification of the conserved Dsn1 kinetochore protein. We find that the Mub1/Ubr2 ubiquitin ligase complex associates with kinetochore particles through the CENP-CMif2 protein. Although Mub1/Ubr2 are not stable kinetochore components in vivo, they regulate the levels of the conserved outer kinetochore protein Dsn1 via ubiquitylation. Strikingly, a deletion of Mub1/Ubr2 restores the levels and viability of a mutant Dsn1 protein, reminiscent of quality control systems that target aberrant proteins for degradation. Consistent with this, Mub1/Ubr2 help to maintain viability when kinetochores are defective. Together, our data identify a previously unknown regulatory mechanism for the conserved Dsn1 kinetochore protein. We propose that Mub1/Ubr2 are part of a quality control system that monitors kinetochore integrity, thus ensuring genomic stability. The flawless execution of cell division is essential to the survival of all organisms. The loss or gain of a single chromosome, the state called aneuploidy, is a hallmark of cancer cells and is the leading cause of spontaneous miscarriages and hereditary birth defects. Segregation is mediated by the kinetochore, the macromolecular complex that assembles on each chromosome and attaches to spindle microtubules to pull chromosomes to opposite poles when cells divide. It is therefore critical to understand how kinetochores are assembled and maintained. Here, we find that the levels of a conserved kinetochore protein are regulated by proteolysis. We propose that cells have quality control systems that ensure kinetochore integrity and thus genome stability.
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82
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Lui DY, Colaiácovo MP. Meiotic development in Caenorhabditis elegans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 757:133-70. [PMID: 22872477 DOI: 10.1007/978-1-4614-4015-4_6] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Caenorhabditis elegans has become a powerful experimental organism with which to study meiotic processes that promote the accurate segregation of chromosomes during the generation of haploid gametes. Haploid reproductive cells are produced through one round of chromosome replication followed by two -successive cell divisions. Characteristic meiotic chromosome structure and dynamics are largely conserved in C. elegans. Chromosomes adopt a meiosis-specific structure by loading cohesin proteins, assembling axial elements, and acquiring chromatin marks. Homologous chromosomes pair and form physical connections though synapsis and recombination. Synaptonemal complex and crossover formation allow for the homologs to stably associate prior to remodeling that facilitates their segregation. This chapter will cover conserved meiotic processes as well as highlight aspects of meiosis that are unique to C. elegans.
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Affiliation(s)
- Doris Y Lui
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
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83
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Kerr GW, Sarkar S, Arumugam P. How to halve ploidy: lessons from budding yeast meiosis. Cell Mol Life Sci 2012; 69:3037-51. [PMID: 22481439 PMCID: PMC11114884 DOI: 10.1007/s00018-012-0974-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 03/09/2012] [Accepted: 03/13/2012] [Indexed: 11/26/2022]
Abstract
Maintenance of ploidy in sexually reproducing organisms requires a specialized form of cell division called meiosis that generates genetically diverse haploid gametes from diploid germ cells. Meiotic cells halve their ploidy by undergoing two rounds of nuclear division (meiosis I and II) after a single round of DNA replication. Research in Saccharomyces cerevisiae (budding yeast) has shown that four major deviations from the mitotic cell cycle during meiosis are essential for halving ploidy. The deviations are (1) formation of a link between homologous chromosomes by crossover, (2) monopolar attachment of sister kinetochores during meiosis I, (3) protection of centromeric cohesion during meiosis I, and (4) suppression of DNA replication following exit from meiosis I. In this review we present the current understanding of the above four processes in budding yeast and examine the possible conservation of molecular mechanisms from yeast to humans.
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Affiliation(s)
- Gary William Kerr
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK.
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84
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Tzur YB, Egydio de Carvalho C, Nadarajan S, Van Bostelen I, Gu Y, Chu DS, Cheeseman IM, Colaiácovo MP. LAB-1 targets PP1 and restricts Aurora B kinase upon entrance into meiosis to promote sister chromatid cohesion. PLoS Biol 2012; 10:e1001378. [PMID: 22927794 PMCID: PMC3424243 DOI: 10.1371/journal.pbio.1001378] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 07/11/2012] [Indexed: 11/19/2022] Open
Abstract
At the onset of the first meiotic division, the protein LAB-1 recruits the PP1 phosphatase to cohesion complexes, preventing Aurora B kinase from targeting cohesins for degradation prematurely and thereby ensuring proper progression of meiotic events in C. elegans. Successful execution of the meiotic program depends on the timely establishment and removal of sister chromatid cohesion. LAB-1 has been proposed to act in the latter by preventing the premature removal of the meiosis-specific cohesin REC-8 at metaphase I in C. elegans, yet the mechanism and scope of LAB-1 function remained unknown. Here we identify an unexpected earlier role for LAB-1 in promoting the establishment of sister chromatid cohesion in prophase I. LAB-1 and REC-8 are both required for the chromosomal association of the cohesin complex subunit SMC-3. Depletion of lab-1 results in partial loss of sister chromatid cohesion in rec-8 and coh-4 coh-3 mutants and further enhanced chromatid dissociation in worms where all three kleisins are mutated. Moreover, lab-1 depletion results in increased Aurora B kinase (AIR-2) signals in early prophase I nuclei, coupled with a parallel decrease in signals for the PP1 homolog, GSP-2. Finally, LAB-1 directly interacts with GSP-1 and GSP-2. We propose that LAB-1 targets the PP1 homologs to the chromatin at the onset of meiosis I, thereby antagonizing AIR-2 and cooperating with the cohesin complex to promote sister chromatid association and normal progression of the meiotic program. A critical step for achieving successful cell division is the regulation of how the cohesin complexes that bind sister chromatids are initially deposited, then maintained, and finally removed to allow the chromatids to separate into daughter cells. This is particularly challenging during meiosis, when the sister chromatids must remain partially connected to each other through the first division. In organisms that have a single focal centromere on each chromosome, such as mammals and flies, cohesin is protected through the first meiotic division by the protein Shugoshin, which binds the PP2A phosphatase. PP2A counteracts phosphorylation by the Aurora B kinase; if certain cohesins are phosphorylated by Aurora B they become targeted for removal, which allows the chromatids to separate. In the nematode C. elegans, the chromosomes lack a localized centromere and the predicted Shugoshin homolog is not required for protection of cohesins; instead, this function is executed in metaphase of the first meiotic division by the protein LAB-1. But it is not completely understood what leads to the deposition of cohesin prior to entry into meiosis and to its maintenance throughout early meiosis I. In this study, we show that LAB-1 is also required for the loading and maintenance of the cohesin complex. LAB-1 ensures that the chromatids are not separated prematurely, and thus enables the proper progression of events through prophase I of meiosis. We propose that LAB-1 may act at the onset of meiosis in a manner akin to Shugoshin, by recruiting the PP1 phosphatase to counteract Aurora B kinase, thereby ensuring sister chromatid cohesion.
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Affiliation(s)
- Yonatan B. Tzur
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | | | - Saravanapriah Nadarajan
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Ivo Van Bostelen
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yanjie Gu
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Diana S. Chu
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Iain M. Cheeseman
- Whitehead Institute for Biomedical Research, and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Monica P. Colaiácovo
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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85
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Yao Y, Dai W. Shugoshins function as a guardian for chromosomal stability in nuclear division. Cell Cycle 2012; 11:2631-42. [PMID: 22732496 PMCID: PMC3850027 DOI: 10.4161/cc.20633] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 05/04/2012] [Indexed: 11/19/2022] Open
Abstract
Accurate chromosome segregation during mitosis and meiosis is regulated and secured by several distinctly different yet intricately connected regulatory mechanisms. As chromosomal instability is a hallmark of a majority of tumors as well as a cause of infertility for germ cells, extensive research in the past has focused on the identification and characterization of molecular components that are crucial for faithful chromosome segregation during cell division. Shugoshins, including Sgo1 and Sgo2, are evolutionarily conserved proteins that function to protect sister chromatid cohesion, thus ensuring chromosomal stability during mitosis and meiosis in eukaryotes. Recent studies reveal that Shugoshins in higher animals play an essential role not only in protecting centromeric cohesion of sister chromatids and assisting bi-orientation attachment at the kinetochores, but also in safeguarding centriole cohesion/engagement during early mitosis. Many molecular components have been identified that play essential roles in modulating/mediating Sgo functions. This review primarily summarizes recent advances on the mechanisms of action of Shugoshins in suppressing chromosomal instability during nuclear division in eukaryotic organisms.
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Affiliation(s)
- Yixin Yao
- Departments of Environmental Medicine and Pharmacology; New York University School of Medicine; Tuxedo, NY USA
| | - Wei Dai
- Departments of Environmental Medicine and Pharmacology; New York University School of Medicine; Tuxedo, NY USA
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86
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Gutiérrez-Caballero C, Cebollero LR, Pendás AM. Shugoshins: from protectors of cohesion to versatile adaptors at the centromere. Trends Genet 2012; 28:351-60. [PMID: 22542109 DOI: 10.1016/j.tig.2012.03.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 03/07/2012] [Accepted: 03/07/2012] [Indexed: 11/20/2022]
Abstract
Sister chromatids are held together by a protein complex named cohesin. Shugoshin proteins protect cohesin from cleavage by separase during meiosis I in eukaryotes and from phosphorylation-mediated removal during mitosis in vertebrates. This protection is crucial for chromosome segregation during mitosis and meiosis. Mechanistically, shugoshins shield cohesin by forming a complex with the phosphatase PP2A, which dephosphorylates cohesin, leading to its retention at centromeres during the onset of meiotic anaphase and vertebrate mitotic prophase I. In addition to this canonical function, shugoshins have evolved novel, species-specific cellular functions, the mechanisms of which remain a subject of intense debate, but are likely to involve spatio-temporally coordinated interactions with the chromosome passenger complex, the spindle checkpoint and the anaphase promoting complex. Here, we compare and contrast these remarkable features of shugoshins in model organisms and humans.
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Affiliation(s)
- Cristina Gutiérrez-Caballero
- Instituto de Biología Molecular y Celular del Cáncer (CSIC-USAL), Campus Miguel de Unamuno, 37007 Salamanca, Spain
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87
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Watanabe Y. Geometry and force behind kinetochore orientation: lessons from meiosis. Nat Rev Mol Cell Biol 2012; 13:370-82. [PMID: 22588367 DOI: 10.1038/nrm3349] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
During mitosis, replicated chromosomes (sister chromatids) become attached at the kinetochore by spindle microtubules emanating from opposite poles and segregate equationally. In the first division of meiosis, however, sister chromatids become attached from the same pole and co-segregate, whereas homologous chromosomes connected by chiasmata segregate to opposite poles. Disorder in this specialized chromosome attachment in meiosis is the leading cause of miscarriage in humans. Recent studies have elucidated the molecular mechanisms determining chromosome orientation, and consequently segregation, in meiosis. Comparative studies of meiosis and mitosis have led to the general principle that kinetochore geometry and tension exerted by microtubules synergistically generate chromosome orientation.
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Affiliation(s)
- Yoshinori Watanabe
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi, Tokyo 113-0032, Japan.
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88
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Rivera T, Ghenoiu C, Rodríguez-Corsino M, Mochida S, Funabiki H, Losada A. Xenopus Shugoshin 2 regulates the spindle assembly pathway mediated by the chromosomal passenger complex. EMBO J 2012; 31:1467-79. [PMID: 22274615 PMCID: PMC3321187 DOI: 10.1038/emboj.2012.4] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 12/22/2011] [Indexed: 12/13/2022] Open
Abstract
Shugoshins (Sgo) are conserved proteins that act as protectors of centromeric cohesion and as sensors of tension for the machinery that eliminates improper kinetochore-microtubule attachments. Most vertebrates contain two Sgo proteins, but their specific functions are not always clear. Xenopus laevis Sgo1, XSgo1, protects centromeric cohesin from the prophase dissociation pathway. Here, we report the identification of XSgo2 and show that it does not regulate cohesion. Instead, we find that it participates in bipolar spindle assembly. Both Sgo proteins interact physically with the Chromosomal Passenger Complex (CPC) containing Aurora B, a key regulator of mitosis, but the functional consequences of such interaction are distinct. XSgo1 is required for proper localization of the CPC while XSgo2 positively contributes to its activation and the subsequent phosphorylation of at least one key substrate for bipolar spindle assembly, the microtubule depolymerizing kinesin MCAK (Mitotic Centromere-Associated Kinesin). Thus, the two Xenopus Sgo proteins have non-overlapping functions in chromosome segregation. Our results further suggest that this functional specificity could rely on the association of XSgo1 and XSgo2 with different regulatory subunits of the PP2A complex.
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Affiliation(s)
- Teresa Rivera
- Chromosome Dynamics Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Cristina Ghenoiu
- Laboratory of Chromosome and Cell Biology, The Rockefeller University, New York, NY, USA
- Department of Molecular Biology, Weill Cornell Graduate School of Biomedical Sciences, Cornell Medical School, New York, NY, USA
| | - Miriam Rodríguez-Corsino
- Chromosome Dynamics Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Satoru Mochida
- Cell Cycle Control Group, Kumamoto University, Kumamoto City, Japan
| | - Hironori Funabiki
- Laboratory of Chromosome and Cell Biology, The Rockefeller University, New York, NY, USA
| | - Ana Losada
- Chromosome Dynamics Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
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89
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Hamza A, Baetz K. Iron-responsive transcription factor Aft1 interacts with kinetochore protein Iml3 and promotes pericentromeric cohesin. J Biol Chem 2012; 287:4139-47. [PMID: 22157760 PMCID: PMC3281692 DOI: 10.1074/jbc.m111.319319] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 12/06/2011] [Indexed: 12/27/2022] Open
Abstract
The Saccharomyces cerevisiae iron-responsive transcription factor, Aft1, has a well established role in regulating iron homeostasis through the transcriptional induction of iron-regulon genes. However, recent studies have implicated Aft1 in other cellular processes independent of iron regulation such as chromosome stability. In addition, chromosome spreads and two-hybrid data suggest that Aft1 interacts with and co-localizes with kinetochore proteins; however, the cellular implications of this have not been established. Here, we demonstrate that Aft1 associates with the kinetochore complex through Iml3. Furthermore, like Iml3, Aft1 is required for the increased association of cohesin with pericentric chromatin, which is required to resist microtubule tension, and aft1Δ cells display chromosome segregation defects in meiosis. Our work defines a new role for Aft1 in chromosome stability and transmission.
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Affiliation(s)
- Akil Hamza
- From the Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Kristin Baetz
- From the Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
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90
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Peraza-Reyes L, Arnaise S, Zickler D, Coppin E, Debuchy R, Berteaux-Lecellier V. The importomer peroxins are differentially required for peroxisome assembly and meiotic development in Podospora anserina: insights into a new peroxisome import pathway. Mol Microbiol 2011; 82:365-77. [PMID: 21895788 DOI: 10.1111/j.1365-2958.2011.07816.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Peroxisome biogenesis relies on two known peroxisome matrix protein import pathways that are mediated by the receptors PEX5 and PEX7. These pathways converge at the importomer, a peroxisome-membrane complex that is required for protein translocation into peroxisomes and consists of docking and RING-finger subcomplexes. In the fungus Podospora anserina, the RING-finger peroxins are crucial for meiocyte formation, while PEX5, PEX7 or the docking peroxin PEX14 are not. Here we show that PEX14 and the PEX14-related protein PEX14/17 are differentially involved in peroxisome import during development. PEX14/17 activity does not compensate for loss of PEX14 function, and elimination of both proteins has no effect on meiocyte differentiation. In contrast, the docking peroxin PEX13, and the peroxins implicated in peroxisome membrane biogenesis PEX3 and PEX19, are required for meiocyte formation. Remarkably, the PTS2 coreceptor PEX20 is also essential for meiocyte differentiation and this function does not require PEX5 or PEX7. This finding suggests that PEX20 can mediate the import receptor activity of specific peroxisome matrix proteins. Our results suggest a new pathway for peroxisome import, which relies on PEX20 as import receptor and which seems critically required for specific developmental processes, like meiocyte differentiation in P. anserina.
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Affiliation(s)
- Leonardo Peraza-Reyes
- Institut de Génétique et Microbiologie, Univ. Paris-Sud, UMR8621, F-91405 Orsay, France.
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91
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Zou H. The sister bonding of duplicated chromosomes. Semin Cell Dev Biol 2011; 22:566-71. [PMID: 21497666 PMCID: PMC3142318 DOI: 10.1016/j.semcdb.2011.03.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 03/23/2011] [Accepted: 03/30/2011] [Indexed: 11/21/2022]
Abstract
Sister chromatid cohesion and separation are two fundamental chromosome dynamics that are essential to equal chromosome segregation during cell proliferation. In this review, I will discuss the major steps that regulate these dynamics during mitosis, with an emphasis on vertebrate cells. The implications of these machineries outside of sister chromatid cohesion and separation are also discussed.
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Affiliation(s)
- Hui Zou
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75252-9148, United States.
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92
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A Screen for Germination Mutants in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2011; 1:143-9. [PMID: 22384326 PMCID: PMC3276131 DOI: 10.1534/g3.111.000323] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 05/13/2011] [Indexed: 11/29/2022]
Abstract
Spore germination in Saccharomyces cerevisiae is a process in which a quiescent cell begins to divide. During germination, the cell undergoes dramatic changes in cell wall and membrane composition, as well as in gene expression. To understand germination in greater detail, we screened the S. cerevisiae deletion set for germination mutants. Our results identified two genes, TRF4 and ERG6, that are required for normal germination on solid media. TRF4 is a member of the TRAMP complex that, together with the exosome, degrades RNA polymerase II transcripts. ERG6 encodes a key step in ergosterol biosynthesis. Taken together, these results demonstrate the complex nature of germination and two genes important in the process.
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93
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Tsuchiya D, Gonzalez C, Lacefield S. The spindle checkpoint protein Mad2 regulates APC/C activity during prometaphase and metaphase of meiosis I in Saccharomyces cerevisiae. Mol Biol Cell 2011; 22:2848-61. [PMID: 21697504 PMCID: PMC3154881 DOI: 10.1091/mbc.e11-04-0378] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The spindle checkpoint protein Mad2 sets the duration of meiosis I by down-regulating APC/C activity to ensure the timely degradation of APC/C substrates. In the absence of Mad2, premature APC/C activity can cause misregulation of meiotic cell cycle events, resulting in chromosome missegregation. In many eukaryotes, disruption of the spindle checkpoint protein Mad2 results in an increase in meiosis I nondisjunction, suggesting that Mad2 has a conserved role in ensuring faithful chromosome segregation in meiosis. To characterize the meiotic function of Mad2, we analyzed individual budding yeast cells undergoing meiosis. We find that Mad2 sets the duration of meiosis I by regulating the activity of APCCdc20. In the absence of Mad2, most cells undergo both meiotic divisions, but securin, a substrate of the APC/C, is degraded prematurely, and prometaphase I/metaphase I is accelerated. Some mad2Δ cells have a misregulation of meiotic cell cycle events and undergo a single aberrant division in which sister chromatids separate. In these cells, both APCCdc20 and APCAma1 are prematurely active, and meiosis I and meiosis II events occur in a single meiotic division. We show that Mad2 indirectly regulates APCAma1 activity by decreasing APCCdc20 activity. We propose that Mad2 is an important meiotic cell cycle regulator that ensures the timely degradation of APC/C substrates and the proper orchestration of the meiotic divisions.
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Affiliation(s)
- Dai Tsuchiya
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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94
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Rumpf C, Cipak L, Dudas A, Benko Z, Pozgajova M, Riedel CG, Ammerer G, Mechtler K, Gregan J. Casein kinase 1 is required for efficient removal of Rec8 during meiosis I. Cell Cycle 2011; 9:2657-62. [PMID: 20581463 DOI: 10.4161/cc.9.13.12146] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Segregation of chromosomes during meiosis depends on separase cleavage of Rec8, the meiosis-specific alpha-kleisin subunit of cohesin. We mapped Rec8 phosphorylation sites by mass spectrometry and show that Rec8 phosphorylation is required for proper chromosome disjunction during meiosis. We further show that the fission yeast casein kinase 1 (CK1) delta/epsilon isoforms Hhp1 and Hhp2 are required for full levels of Rec8 phosphorylation and for efficient removal of Rec8 at the onset of anaphase I. Our data are consistent with the model that Hhp1/Hhp2-dependent phosphorylation of Rec8 is required for separase-mediated cleavage of Rec8 during meiosis I.
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Affiliation(s)
- Cornelia Rumpf
- Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
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95
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Abstract
The increasing use of high-throughput technologies and computational modeling is revealing new levels of biological function and organization. How are these features of systems biology influencing our view of the cell?
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Affiliation(s)
- Paul Nurse
- Cancer Research UK, London Research Institute, 44, Lincoln's Inn Fields, London UK WC2A 3LY, UK.
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96
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A novel tumor-derived SGOL1 variant causes abnormal mitosis and unstable chromatid cohesion. Oncogene 2011; 30:4453-63. [DOI: 10.1038/onc.2011.152] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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97
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Involvement of the Saccharomyces cerevisiae hydrolase Ldh1p in lipid homeostasis. EUKARYOTIC CELL 2011; 10:776-81. [PMID: 21478434 DOI: 10.1128/ec.05040-11] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Here, we report the functional characterization of the newly identified lipid droplet hydrolase Ldh1p. Recombinant Ldh1p exhibits esterase and triacylglycerol lipase activities. Mutation of the serine in the hydrolase/lipase motif GXSXG completely abolished esterase activity. Ldh1p is required for the maintenance of a steady-state level of the nonpolar and polar lipids of lipid droplets. A characteristic feature of the Saccharomyces cerevisiae Δldh1 strain is the appearance of giant lipid droplets and an excessive accumulation of nonpolar lipids and phospholipids upon growth on medium containing oleic acid as a sole carbon source. Ldh1p is thought to play a role in maintaining the lipid homeostasis in yeast by regulating both phospholipid and nonpolar lipid levels.
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98
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Dudas A, Ahmad S, Gregan J. Sgo1 is required for co-segregation of sister chromatids during achiasmate meiosis I. Cell Cycle 2011; 10:951-5. [PMID: 21330786 DOI: 10.4161/cc.10.6.15032] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The reduction of chromosome number during meiosis is achieved by two successive rounds of chromosome segregation, called meiosis I and meiosis II. While meiosis II is similar to mitosis in that sister kinetochores are bi-oriented and segregate to opposite poles, recombined homologous chromosomes segregate during the first meiotic division. Formation of chiasmata, mono-orientation of sister kinetochores and protection of centromeric cohesion are three major features of meiosis I chromosomes which ensure the reductional nature of chromosome segregation. Here we show that sister chromatids frequently segregate to opposite poles during meiosis I in fission yeast cells that lack both chiasmata and the protector of centromeric cohesion Sgo1. Our data are consistent with the notion that sister kinetochores are frequently bi-oriented in the absence of chiasmata and that Sgo1 prevents equational segregation of sister chromatids during achiasmate meiosis I.
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Affiliation(s)
- Andrej Dudas
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Austria
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99
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Hirose Y, Suzuki R, Ohba T, Hinohara Y, Matsuhara H, Yoshida M, Itabashi Y, Murakami H, Yamamoto A. Chiasmata promote monopolar attachment of sister chromatids and their co-segregation toward the proper pole during meiosis I. PLoS Genet 2011; 7:e1001329. [PMID: 21423721 PMCID: PMC3053323 DOI: 10.1371/journal.pgen.1001329] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Accepted: 02/08/2011] [Indexed: 11/18/2022] Open
Abstract
The chiasma is a structure that forms between a pair of homologous chromosomes by crossover recombination and physically links the homologous chromosomes during meiosis. Chiasmata are essential for the attachment of the homologous chromosomes to opposite spindle poles (bipolar attachment) and their subsequent segregation to the opposite poles during meiosis I. However, the overall function of chiasmata during meiosis is not fully understood. Here, we show that chiasmata also play a crucial role in the attachment of sister chromatids to the same spindle pole and in their co-segregation during meiosis I in fission yeast. Analysis of cells lacking chiasmata and the cohesin protector Sgo1 showed that loss of chiasmata causes frequent bipolar attachment of sister chromatids during anaphase. Furthermore, high time-resolution analysis of centromere dynamics in various types of chiasmate and achiasmate cells, including those lacking the DNA replication checkpoint factor Mrc1 or the meiotic centromere protein Moa1, showed the following three outcomes: (i) during the pre-anaphase stage, the bipolar attachment of sister chromatids occurs irrespective of chiasma formation; (ii) the chiasma contributes to the elimination of the pre-anaphase bipolar attachment; and (iii) when the bipolar attachment remains during anaphase, the chiasmata generate a bias toward the proper pole during poleward chromosome pulling that results in appropriate chromosome segregation. Based on these results, we propose that chiasmata play a pivotal role in the selection of proper attachments and provide a backup mechanism that promotes correct chromosome segregation when improper attachments remain during anaphase I.
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Affiliation(s)
- Yukinobu Hirose
- The Department of Chemistry, Shizuoka University, Shizuoka, Japan
| | - Ren Suzuki
- The Department of Chemistry, Shizuoka University, Shizuoka, Japan
| | - Tatsunori Ohba
- The Department of Chemistry, Shizuoka University, Shizuoka, Japan
| | - Yumi Hinohara
- The Department of Chemistry, Shizuoka University, Shizuoka, Japan
| | | | - Masashi Yoshida
- The Department of Chemistry, Shizuoka University, Shizuoka, Japan
| | - Yuta Itabashi
- The Department of Chemistry, Shizuoka University, Shizuoka, Japan
| | - Hiroshi Murakami
- Department of Biochemistry and Cell Biology, Graduate School of Medicine, Nagoya City University, Nagoya, Japan
| | - Ayumu Yamamoto
- The Department of Chemistry, Shizuoka University, Shizuoka, Japan
- * E-mail:
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100
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Sustained and rapid chromosome movements are critical for chromosome pairing and meiotic progression in budding yeast. Genetics 2011; 188:21-32. [PMID: 21339478 DOI: 10.1534/genetics.110.125575] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Telomere-led chromosome movements are a conserved feature of meiosis I (MI) prophase. Several roles have been proposed for such chromosome motion, including promoting homolog pairing and removing inappropriate chromosomal interactions. Here, we provide evidence in budding yeast that rapid chromosome movements affect homolog pairing and recombination. We found that csm4Δ strains, which are defective for telomere-led chromosome movements, show defects in homolog pairing as measured in a "one-dot/two-dot tetR-GFP" assay; however, pairing in csm4Δ eventually reaches near wild-type (WT) levels. Charged-to-alanine scanning mutagenesis of CSM4 yielded one allele, csm4-3, that confers a csm4Δ-like delay in meiotic prophase but promotes high spore viability. The meiotic delay in csm4-3 strains is essential for spore viability because a null mutation (rad17Δ) in the Rad17 checkpoint protein suppresses the delay but confers a severe spore viability defect. csm4-3 mutants show a general defect in chromosome motion but an intermediate defect in chromosome pairing. Chromosome velocity analysis in live cells showed that while average chromosome velocity was strongly reduced in csm4-3, chromosomes in this mutant displayed occasional rapid movements. Lastly, we observed that spo11 mutants displaying lower levels of meiosis-induced double-strand breaks showed higher spore viability in the presence of the csm4-3 mutation compared to csm4Δ. On the basis of these observations, we propose that during meiotic prophase the presence of occasional fast moving chromosomes over an extended period of time is sufficient to promote WT levels of recombination and high spore viability; however, sustained and rapid chromosome movements are required to prevent a checkpoint response and promote efficient meiotic progression.
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