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1.
Nat Commun ; 11(1): 4917, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-33004802

RESUMO

Maternal mRNA clearance is an essential process that occurs during maternal-to-zygotic transition (MZT). However, the dynamics, functional importance, and pathological relevance of maternal mRNA decay in human preimplantation embryos have not yet been analyzed. Here we report the zygotic genome activation (ZGA)-dependent and -independent maternal mRNA clearance processes during human MZT and demonstrate that subgroups of human maternal transcripts are sequentially removed by maternal (M)- and zygotic (Z)-decay pathways before and after ZGA. Key factors regulating M-decay and Z-decay pathways in mouse have similar expression pattern during human MZT, suggesting that YAP1-TEAD4 transcription activators, TUT4/7-mediated mRNA 3'-oligouridylation, and BTG4/CCR4-NOT-induced mRNA deadenylation may also be involved in the regulation of human maternal mRNA stability. Decreased expression of these factors and abnormal accumulation of maternal transcripts are observed in the development-arrested embryos of patients who seek assisted reproduction. Defects of M-decay and Z-decay are detected with high incidence in embryos that are arrested at the zygote and 8-cell stages, respectively. In addition, M-decay is not found to be affected by maternal TUBB8 mutations, although these mutations cause meiotic cell division defects and zygotic arrest, which indicates that mRNA decay is regulated independent of meiotic spindle assembly. Considering the correlations between maternal mRNA decay defects and early developmental arrest of in vitro fertilized human embryos, M-decay and Z-decay pathway activities may contribute to the developmental potential of human preimplantation embryos.


Assuntos
Blastocisto/metabolismo , Desenvolvimento Embrionário/fisiologia , Estabilidade de RNA/fisiologia , RNA Mensageiro Estocado/metabolismo , Fatores de Transcrição/metabolismo , Adulto , Animais , Técnicas de Cultura Embrionária , Feminino , Fertilização In Vitro/métodos , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Masculino , Meiose/genética , Camundongos , Mutação , Oócitos/metabolismo , Cultura Primária de Células , RNA-Seq , Tubulina (Proteína)/genética , Zigoto/metabolismo
2.
PLoS Genet ; 16(9): e1009048, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32931493

RESUMO

During meiotic prophase, sister chromatids are organized into axial element (AE), which underlies the structural framework for the meiotic events such as meiotic recombination and homolog synapsis. HORMA domain-containing proteins (HORMADs) localize along AE and play critical roles in the regulation of those meiotic events. Organization of AE is attributed to two groups of proteins: meiotic cohesins REC8 and RAD21L; and AE components SYCP2 and SYCP3. It has been elusive how these chromosome structural proteins contribute to the chromatin loading of HORMADs prior to AE formation. Here we newly generated Sycp2 null mice and showed that initial chromatin loading of HORMAD1 was mediated by meiotic cohesins prior to AE formation. HORMAD1 interacted not only with the AE components SYCP2 and SYCP3 but also with meiotic cohesins. Notably, HORMAD1 interacted with meiotic cohesins even in Sycp2-KO, and localized along cohesin axial cores independently of the AE components SYCP2 and SYCP3. Hormad1/Rad21L-double knockout (dKO) showed more severe defects in the formation of synaptonemal complex (SC) compared to Hormad1-KO or Rad21L-KO. Intriguingly, Hormad1/Rec8-dKO but not Hormad1/Rad21L-dKO showed precocious separation of sister chromatid axis. These findings suggest that meiotic cohesins REC8 and RAD21L mediate chromatin loading and the mode of action of HORMAD1 for synapsis during early meiotic prophase.


Assuntos
Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Animais , Cromátides/genética , Cromátides/metabolismo , Cromatina/metabolismo , Cromossomos/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Feminino , Masculino , Meiose/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Nucleares/genética , Fosfoproteínas/genética , Prófase/genética , Espermatócitos/metabolismo , Complexo Sinaptonêmico/metabolismo
3.
Nat Commun ; 11(1): 4486, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32900989

RESUMO

Centromeres are epigenetically determined nuclear domains strictly required for chromosome segregation and genome stability. However, the mechanisms regulating centromere and kinetochore chromatin modifications are not known. Here, we demonstrate that LSH is enriched at meiotic kinetochores and its targeted deletion induces centromere instability and abnormal chromosome segregation. Superresolution chromatin analysis resolves LSH at the inner centromere and kinetochores during oocyte meiosis. LSH knockout pachytene oocytes exhibit reduced HDAC2 and DNMT-1. Notably, mutant oocytes show a striking increase in histone H3 phosphorylation at threonine 3 (H3T3ph) and accumulation of major satellite transcripts in both prophase-I and metaphase-I chromosomes. Moreover, knockout oocytes exhibit centromere fusions, ectopic kinetochore formation and abnormal exchange of chromatin fibers between paired bivalents and asynapsed chromosomes. Our results indicate that loss of LSH affects the levels and chromosomal localization of H3T3ph and provide evidence that, by maintaining transcriptionally repressive heterochromatin, LSH may be essential to prevent deleterious meiotic recombination events at repetitive centromeric sequences.


Assuntos
DNA Helicases/metabolismo , Meiose/fisiologia , Oócitos/citologia , Oócitos/metabolismo , Animais , Centrômero/genética , Centrômero/metabolismo , DNA Helicases/deficiência , DNA Helicases/genética , Feminino , Histonas/metabolismo , Cinetocoros/metabolismo , Masculino , Meiose/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosforilação , Transcrição Genética
4.
PLoS Genet ; 16(9): e1009001, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32886661

RESUMO

During meiosis, diploid organisms reduce their chromosome number by half to generate haploid gametes. This process depends on the repair of double strand DNA breaks as crossover recombination events between homologous chromosomes, which hold homologs together to ensure their proper segregation to opposite spindle poles during the first meiotic division. Although most organisms are limited in the number of crossovers between homologs by a phenomenon called crossover interference, the consequences of excess interfering crossovers on meiotic chromosome segregation are not well known. Here we show that extra interfering crossovers lead to a range of meiotic defects and we uncover mechanisms that counteract these errors. Using chromosomes that exhibit a high frequency of supernumerary crossovers in Caenorhabditis elegans, we find that essential chromosomal structures are mispatterned in the presence of multiple crossovers, subjecting chromosomes to improper spindle forces and leading to defects in metaphase alignment. Additionally, the chromosomes with extra interfering crossovers often exhibited segregation defects in anaphase I, with a high incidence of chromatin bridges that sometimes created a tether between the chromosome and the first polar body. However, these anaphase I bridges were often able to resolve in a LEM-3 nuclease dependent manner, and chromosome tethers that persisted were frequently resolved during Meiosis II by a second mechanism that preferentially segregates the tethered sister chromatid into the polar body. Altogether these findings demonstrate that excess interfering crossovers can severely impact chromosome patterning and segregation, highlighting the importance of limiting the number of recombination events between homologous chromosomes for the proper execution of meiosis.


Assuntos
Segregação de Cromossomos/genética , Troca Genética/genética , Meiose/genética , Animais , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Cromátides/genética , Cromatina/genética , Posicionamento Cromossômico/genética , Cromossomos/genética , Quebras de DNA de Cadeia Dupla , Endodesoxirribonucleases/genética , Recombinação Genética
5.
Mutat Res ; 785: 108320, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32800274

RESUMO

It is well established that maternal age is associated with a rapid decline in the production of healthy and high-quality oocytes resulting in reduced fertility in women older than 35 years of age. In particular, chromosome segregation errors during meiotic divisions are increasingly common and lead to the production of oocytes with an incorrect number of chromosomes, a condition known as aneuploidy. When an aneuploid oocyte is fertilized by a sperm it gives rise to an aneuploid embryo that, except in rare situations, will result in a spontaneous abortion. As females advance in age, they are at higher risk of infertility, miscarriage, or having a pregnancy affected by congenital birth defects such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Turner syndrome (monosomy X). Here, we review the potential molecular mechanisms associated with increased chromosome segregation errors during meiosis as a function of maternal age. Our review shows that multiple exogenous and endogenous factors contribute to the age-related increase in oocyte aneuploidy. Specifically, the weight of evidence indicates that recombination failure, cohesin deterioration, spindle assembly checkpoint (SAC) disregulation, abnormalities in post-translational modification of histones and tubulin, and mitochondrial dysfunction are the leading causes of oocyte aneuploidy associated with maternal aging. There is also growing evidence that dietary and other bioactive interventions may mitigate the effect of maternal aging on oocyte quality and oocyte aneuploidy, thereby improving fertility outcomes. Maternal age is a major concern for aneuploidy and genetic disorders in the offspring in the context of an increasing proportion of mothers having children at increasingly older ages. A better understanding of the mechanisms associated with maternal aging leading to aneuploidy and of intervention strategies that may mitigate these detrimental effects and reduce its occurrence are essential for preventing abnormal reproductive outcomes in the human population.


Assuntos
Aneuploidia , Proteínas de Ciclo Celular/genética , Proteínas Cromossômicas não Histona/genética , Segregação de Cromossomos/genética , Anormalidades Congênitas/genética , Idade Materna , Anormalidades Congênitas/prevenção & controle , Feminino , Humanos , Pontos de Checagem da Fase M do Ciclo Celular/genética , Meiose/genética , Mitocôndrias/fisiologia , Oócitos/fisiologia
6.
PLoS One ; 15(8): e0236285, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32841250

RESUMO

Characterizing meiotic recombination rates across the genomes of nonhuman primates is important for understanding the genetics of primate populations, performing genetic analyses of phenotypic variation and reconstructing the evolution of human recombination. Rhesus macaques (Macaca mulatta) are the most widely used nonhuman primates in biomedical research. We constructed a high-resolution genetic map of the rhesus genome based on whole genome sequence data from Indian-origin rhesus macaques. The genetic markers used were approximately 18 million SNPs, with marker density 6.93 per kb across the autosomes. We report that the genome-wide recombination rate in rhesus macaques is significantly lower than rates observed in apes or humans, while the distribution of recombination across the macaque genome is more uniform. These observations provide new comparative information regarding the evolution of recombination in primates.


Assuntos
Evolução Molecular , Macaca mulatta/genética , Meiose/genética , Recombinação Genética , Animais , Mapeamento Cromossômico , Marcadores Genéticos , Variação Genética , Genoma , Humanos , Polimorfismo de Nucleotídeo Único , Especificidade da Espécie , Sequenciamento Completo do Genoma
7.
Am J Hum Genet ; 107(2): 342-351, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32673564

RESUMO

Male infertility affects ∼7% of men, but its causes remain poorly understood. The most severe form is non-obstructive azoospermia (NOA), which is, in part, caused by an arrest at meiosis. So far, only a few validated disease-associated genes have been reported. To address this gap, we performed whole-exome sequencing in 58 men with unexplained meiotic arrest and identified the same homozygous frameshift variant c.676dup (p.Trp226LeufsTer4) in M1AP, encoding meiosis 1 associated protein, in three unrelated men. This variant most likely results in a truncated protein as shown in vitro by heterologous expression of mutant M1AP. Next, we screened four large cohorts of infertile men and identified three additional individuals carrying homozygous c.676dup and three carrying combinations of this and other likely causal variants in M1AP. Moreover, a homozygous missense variant, c.1166C>T (p.Pro389Leu), segregated with infertility in five men from a consanguineous Turkish family. The common phenotype between all affected men was NOA, but occasionally spermatids and rarely a few spermatozoa in the semen were observed. A similar phenotype has been described for mice with disruption of M1ap. Collectively, these findings demonstrate that mutations in M1AP are a relatively frequent cause of autosomal recessive severe spermatogenic failure and male infertility with strong clinical validity.


Assuntos
Pontos de Checagem do Ciclo Celular/genética , Infertilidade Masculina/genética , Meiose/genética , Mutação/genética , Proteínas/genética , Espermatogênese/genética , Adulto , Alelos , Animais , Azoospermia/genética , Homozigoto , Humanos , Masculino , Camundongos , Fenótipo , Espermatozoides/anormalidades , Testículo/anormalidades , Turquia , Sequenciamento Completo do Exoma/métodos
8.
J Biosci Bioeng ; 130(4): 367-373, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32646632

RESUMO

Cross hybridization breeding of sake yeasts is hampered by difficulty in acquisition of haploid cells through sporulation. We previously demonstrated that typical sake yeast strains were defective in meiotic chromosome recombination, which caused poor sporulation and loss of spore viability. In this study, we screened a single copy plasmid genomic DNA library of the laboratory Saccharomyces cerevisiae GRF88 for genes that might complement the meiotic recombination defect of UTCAH-3, a strain derived from the sake yeast Kyokai no. 7 (K7). We identified the SPO11 gene of the laboratory strain (ScSPO11), encoding a meiosis-specific endonuclease that catalyzes DNA double-strand breaks required for meiotic recombination, as a gene that restored meiotic recombination and spore viability of UTCAH-3. K7SPO11 could not restore sporulation efficiency and spore viability of UTCAH-3 and a laboratory strain BY4743 spo11Δ/spo11Δ, indicating that K7SPO11 is not functional. Sequence analysis of the SPO11 genes of various Kyokai sake yeasts (K1, and K3-K10) revealed that the K7 group of sake yeasts (K6, K7, K9, and K10) had a mutual missense mutation (C73T) in addition to other three common mutations present in all Kyokai yeasts tested. ScSPO11C73T created through in vitro mutagenesis could not restore spore viability of BY4743 spo11Δ/spo11Δ. On the other hand, K8SPO11, which have the three common mutations except for C73T could restore spore viability of BY4743 spo11Δ/spo11Δ. These results suggest that C73T might be a causative mutation of recombination defect in K7SPO11. Moreover, we found that the introduction of ScRIM15 restored sporulation efficiency but not spore viability.


Assuntos
Bebidas Alcoólicas/microbiologia , Endodesoxirribonucleases/genética , Meiose/genética , Recombinação Genética/genética , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Clonagem Molecular , Quebras de DNA de Cadeia Dupla , Mutação , Saccharomyces cerevisiae/citologia
9.
PLoS Genet ; 16(7): e1008900, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32667955

RESUMO

In this study we performed a genotype-phenotype association analysis of meiotic stability in 10 autotetraploid Arabidopsis lyrata and A. lyrata/A. arenosa hybrid populations collected from the Wachau region and East Austrian Forealps. The aim was to determine the effect of eight meiosis genes under extreme selection upon adaptation to whole genome duplication. Individual plants were genotyped by high-throughput sequencing of the eight meiosis genes (ASY1, ASY3, PDS5b, PRD3, REC8, SMC3, ZYP1a/b) implicated in synaptonemal complex formation and phenotyped by assessing meiotic metaphase I chromosome configurations. Our results reveal that meiotic stability varied greatly (20-100%) between individual tetraploid plants and associated with segregation of a novel ASYNAPSIS3 (ASY3) allele derived from A. lyrata. The ASY3 allele that associates with meiotic stability possesses a putative in-frame tandem duplication (TD) of a serine-rich region upstream of the coiled-coil domain that appears to have arisen at sites of DNA microhomology. The frequency of multivalents observed in plants homozygous for the ASY3 TD haplotype was significantly lower than in plants heterozygous for ASY3 TD/ND (non-duplicated) haplotypes. The chiasma distribution was significantly altered in the stable plants compared to the unstable plants with a shift from proximal and interstitial to predominantly distal locations. The number of HEI10 foci at pachytene that mark class I crossovers was significantly reduced in a plant homozygous for ASY3 TD compared to a plant heterozygous for ASY3 ND/TD. Fifty-eight alleles of the 8 meiosis genes were identified from the 10 populations analysed, demonstrating dynamic population variability at these loci. Widespread chimerism between alleles originating from A. lyrata/A. arenosa and diploid/tetraploids indicates that this group of rapidly evolving genes may provide precise adaptive control over meiotic recombination in the tetraploids, the very process that gave rise to them.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Proteínas Cromossômicas não Histona/genética , Meiose/genética , Alelos , Arabidopsis/crescimento & desenvolvimento , Pareamento Cromossômico/genética , Segregação de Cromossomos , Cromossomos de Plantas/genética , Proteínas de Ligação a DNA/genética , Diploide , Tetraploidia
10.
Gene ; 758: 144966, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32687945

RESUMO

RAD21 (also known as KIAA0078, NXP1, HR21, Mcd1, Scc1, and hereafter called RAD21), an essential gene, encodes a DNA double-strand break (DSB) repair protein that is evolutionarily conserved in all eukaryotes from budding yeast to humans. RAD21 protein is a structural component of the highly conserved cohesin complex consisting of RAD21, SMC1a, SMC3, and SCC3 [STAG1 (SA1) and STAG2 (SA2) in metazoans] proteins, involved in sister chromatid cohesion. This function is essential for proper chromosome segregation, post-replicative DNA repair, and prevention of inappropriate recombination between repetitive regions. In interphase, cohesin also functions in the control of gene expression by binding to numerous sites within the genome. In addition to playing roles in the normal cell cycle and DNA DSB repair, RAD21 is also linked to the apoptotic pathways. Germline heterozygous or homozygous missense mutations in RAD21 have been associated with human genetic disorders, including developmental diseases such as Cornelia de Lange syndrome (CdLS) and chronic intestinal pseudo-obstruction (CIPO) called Mungan syndrome, respectively, and collectively termed as cohesinopathies. Somatic mutations and amplification of the RAD21 have also been widely reported in both human solid and hematopoietic tumors. Considering the role of RAD21 in a broad range of cellular processes that are hot spots in neoplasm, it is not surprising that the deregulation of RAD21 has been increasingly evident in human cancers. Herein, we review the biology of RAD21 and the cellular processes that this important protein regulates and discuss the significance of RAD21 deregulation in cancer and cohesinopathies.


Assuntos
Proteínas de Ciclo Celular/genética , Proteínas Cromossômicas não Histona/genética , Reparo do DNA/genética , Proteínas de Ligação a DNA/genética , Neoplasias/genética , Apoptose/genética , Esôfago de Barrett/genética , Quebras de DNA de Cadeia Dupla , Síndrome de Cornélia de Lange/genética , Hematopoese/genética , Humanos , Pseudo-Obstrução Intestinal/genética , Meiose/genética , Neoplasias/patologia
11.
PLoS Genet ; 16(7): e1008918, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32730246

RESUMO

Holocentric chromosomes possess multiple kinetochores along their length rather than the single centromere typical of other chromosomes [1]. They have been described for the first time in cytogenetic experiments dating from 1935 and, since this first observation, the term holocentric chromosome has referred to chromosomes that: i. lack the primary constriction corresponding to centromere observed in monocentric chromosomes [2]; ii. possess multiple kinetochores dispersed along the chromosomal axis so that microtubules bind to chromosomes along their entire length and move broadside to the pole from the metaphase plate [3]. These chromosomes are also termed holokinetic, because, during cell division, chromatids move apart in parallel and do not form the classical V-shaped figures typical of monocentric chromosomes [4-6]. Holocentric chromosomes evolved several times during both animal and plant evolution and are currently reported in about eight hundred diverse species, including plants, insects, arachnids and nematodes [7,8]. As a consequence of their diffuse kinetochores, holocentric chromosomes may stabilize chromosomal fragments favouring karyotype rearrangements [9,10]. However, holocentric chromosome may also present limitations to crossing over causing a restriction of the number of chiasma in bivalents [11] and may cause a restructuring of meiotic divisions resulting in an inverted meiosis [12].


Assuntos
Caenorhabditis elegans/genética , Cromossomos/genética , Cinetocoros/ultraestrutura , Meiose/genética , Animais , Caenorhabditis elegans/citologia , Centrômero/genética , Centrômero/ultraestrutura , Cromátides/genética , Cromátides/ultraestrutura , Segregação de Cromossomos/genética , Cromossomos/ultraestrutura , Cariótipo , Plantas/genética
12.
PLoS Genet ; 16(7): e1008904, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32730253

RESUMO

The conserved ATPase, PCH-2/TRIP13, is required during both the spindle checkpoint and meiotic prophase. However, its specific role in regulating meiotic homolog pairing, synapsis and recombination has been enigmatic. Here, we report that this enzyme is required to proofread meiotic homolog interactions. We generated a mutant version of PCH-2 in C. elegans that binds ATP but cannot hydrolyze it: pch-2E253Q. In vitro, this mutant can bind a known substrate but is unable to remodel it. This mutation results in some non-homologous synapsis and impaired crossover assurance. Surprisingly, worms with a null mutation in PCH-2's adapter protein, CMT-1, the ortholog of p31comet, localize PCH-2 to meiotic chromosomes, exhibit non-homologous synapsis and lose crossover assurance. The similarity in phenotypes between cmt-1 and pch-2E253Q mutants suggest that PCH-2 can bind its meiotic substrates in the absence of CMT-1, in contrast to its role during the spindle checkpoint, but requires its adapter to hydrolyze ATP and remodel them.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas de Caenorhabditis elegans/genética , Proteínas de Ciclo Celular/genética , Meiose/genética , Proteínas Nucleares/genética , Adenosina Trifosfatases/genética , Trifosfato de Adenosina/genética , Animais , Caenorhabditis elegans/genética , Pareamento Cromossômico/genética , Segregação de Cromossomos/genética , Cromossomos/genética , Humanos , Mutação/genética , Fuso Acromático/genética
13.
Proc Natl Acad Sci U S A ; 117(29): 17130-17134, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32636262

RESUMO

Supergenes underlie striking polymorphisms in nature, yet the evolutionary mechanisms by which they arise and persist remain enigmatic. These clusters of linked loci can spread in populations because they captured coadapted alleles or by selfishly distorting the laws of Mendelian inheritance. Here, we show that the supergene haplotype associated with multiple-queen colonies in Alpine silver ants is a maternal effect killer. All eggs from heterozygous queens failed to hatch when they did not inherit this haplotype. Hence, the haplotype specific to multiple-queen colonies is a selfish genetic element that enhances its own transmission by causing developmental arrest of progeny that do not carry it. At the population level, such transmission ratio distortion favors the spread of multiple-queen colonies, to the detriment of the alternative haplotype associated with single-queen colonies. Hence, selfish gene drive by one haplotype will impact the evolutionary dynamics of alternative forms of colony social organization. This killer hidden in a social supergene shows that large nonrecombining genomic regions are prone to cause multifarious effects across levels of biological organization.


Assuntos
Formigas/genética , Regulação da Expressão Gênica no Desenvolvimento/genética , Genes de Insetos/genética , Herança Materna/genética , Comportamento Social , Animais , Formigas/crescimento & desenvolvimento , Formigas/fisiologia , Evolução Molecular , Feminino , Haplótipos/genética , Masculino , Meiose/genética , Sequências Reguladoras de Ácido Nucleico/genética , Sequências Repetitivas de Ácido Nucleico/genética
14.
Nucleic Acids Res ; 48(15): 8474-8489, 2020 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-32652040

RESUMO

Highly toxic DNA double-strand breaks (DSBs) readily trigger the DNA damage response (DDR) in cells, which delays cell cycle progression to ensure proper DSB repair. In Saccharomyces cerevisiae, mitotic S phase (20-30 min) is lengthened upon DNA damage. During meiosis, Spo11-induced DSB onset and repair lasts up to 5 h. We report that the NH2-terminal domain (NTD; residues 1-66) of Rad51 has dual functions for repairing DSBs during vegetative growth and meiosis. Firstly, Rad51-NTD exhibits autonomous expression-enhancing activity for high-level production of native Rad51 and when fused to exogenous ß-galactosidase in vivo. Secondly, Rad51-NTD is an S/T-Q cluster domain (SCD) harboring three putative Mec1/Tel1 target sites. Mec1/Tel1-dependent phosphorylation antagonizes the proteasomal degradation pathway, increasing the half-life of Rad51 from ∼30 min to ≥180 min. Our results evidence a direct link between homologous recombination and DDR modulated by Rad51 homeostasis.


Assuntos
Quebras de DNA de Cadeia Dupla , Endodesoxirribonucleases/genética , Meiose/genética , Rad51 Recombinase/genética , Proteínas de Saccharomyces cerevisiae/genética , Dano ao DNA/genética , Reparo do DNA/genética , Proteínas de Ligação a DNA/genética , Regulação Fúngica da Expressão Gênica/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Fosforilação/genética , Complexo de Endopeptidases do Proteassoma/genética , Domínios Proteicos/genética , Proteínas Serina-Treonina Quinases/genética , Proteólise , Saccharomyces cerevisiae/genética , beta-Galactosidase/genética
15.
Nature ; 583(7815): 259-264, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32494014

RESUMO

Meiosis, although essential for reproduction, is also variable and error-prone: rates of chromosome crossover vary among gametes, between the sexes, and among humans of the same sex, and chromosome missegregation leads to abnormal chromosome numbers (aneuploidy)1-8. To study diverse meiotic outcomes and how they covary across chromosomes, gametes and humans, we developed Sperm-seq, a way of simultaneously analysing the genomes of thousands of individual sperm. Here we analyse the genomes of 31,228 human gametes from 20 sperm donors, identifying 813,122 crossovers and 787 aneuploid chromosomes. Sperm donors had aneuploidy rates ranging from 0.01 to 0.05 aneuploidies per gamete; crossovers partially protected chromosomes from nondisjunction at the meiosis I cell division. Some chromosomes and donors underwent more-frequent nondisjunction during meiosis I, and others showed more meiosis II segregation failures. Sperm genomes also manifested many genomic anomalies that could not be explained by simple nondisjunction. Diverse recombination phenotypes-from crossover rates to crossover location and separation, a measure of crossover interference-covaried strongly across individuals and cells. Our results can be incorporated with earlier observations into a unified model in which a core mechanism, the variable physical compaction of meiotic chromosomes, generates interindividual and cell-to-cell variation in diverse meiotic phenotypes.


Assuntos
Genoma Humano/genética , Meiose/genética , Espermatozoides/citologia , Espermatozoides/metabolismo , Adolescente , Adulto , Alelos , Aneuploidia , Troca Genética/genética , Haplótipos/genética , Humanos , Masculino , Não Disjunção Genética , Análise de Célula Única , Doadores de Tecidos , Adulto Jovem
16.
PLoS Genet ; 16(6): e1008849, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32516352

RESUMO

Cohesin, a multisubunit protein complex, is required for holding sister chromatids together during mitosis and meiosis. The recruitment of cohesin by the sister chromatid cohesion 2/4 (SCC2/4) complex has been extensively studied in Saccharomyces cerevisiae mitosis, but its role in mitosis and meiosis remains poorly understood in multicellular organisms, because complete loss-of-function of either gene causes embryonic lethality. Here, we identified a weak allele of Atscc2 (Atscc2-5) that has only minor defects in vegetative development but exhibits a significant reduction in fertility. Cytological analyses of Atscc2-5 reveal multiple meiotic phenotypes including defects in chromosomal axis formation, meiosis-specific cohesin loading, homolog pairing and synapsis, and AtSPO11-1-dependent double strand break repair. Surprisingly, even though AtSCC2 interacts with AtSCC4 in vitro and in vivo, meiosis-specific knockdown of AtSCC4 expression does not cause any meiotic defect, suggesting that the SCC2-SCC4 complex has divergent roles in mitosis and meiosis. SCC2 homologs from land plants have a unique plant homeodomain (PHD) motif not found in other species. We show that the AtSCC2 PHD domain can bind to the N terminus of histones and is required for meiosis but not mitosis. Taken together, our results provide evidence that unlike SCC2 in other organisms, SCC2 requires a functional PHD domain during meiosis in land plants.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Proteínas de Transporte/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Meiose/genética , Dedos de Zinco PHD/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Proteínas de Transporte/metabolismo , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/genética , Proteínas Cromossômicas não Histona/química , Proteínas Cromossômicas não Histona/genética , Técnicas de Silenciamento de Genes , Genoma de Planta/genética , Mutação com Perda de Função , Mitose/genética , Morfogênese/genética , Mutagênese , Plantas Geneticamente Modificadas , Polinização/genética , Sequenciamento Completo do Genoma
17.
Nat Commun ; 11(1): 3101, 2020 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-32555348

RESUMO

Orderly chromosome segregation is enabled by crossovers between homologous chromosomes in the first meiotic division. Crossovers arise from recombination-mediated repair of programmed DNA double-strand breaks (DSBs). Multiple DSBs initiate recombination, and most are repaired without crossover formation, although one or more generate crossovers on each chromosome. Although the underlying mechanisms are ill-defined, the differentiation and maturation of crossover-specific recombination intermediates requires the cyclin-like CNTD1. Here, we identify PRR19 as a partner of CNTD1. We find that, like CNTD1, PRR19 is required for timely DSB repair and the formation of crossover-specific recombination complexes. PRR19 and CNTD1 co-localise at crossover sites, physically interact, and are interdependent for accumulation, indicating a PRR19-CNTD1 partnership in crossing over. Further, we show that CNTD1 interacts with a cyclin-dependent kinase, CDK2, which also accumulates in crossover-specific recombination complexes. Thus, the PRR19-CNTD1 complex may enable crossover differentiation by regulating CDK2.


Assuntos
Troca Genética/genética , Ciclinas/genética , Quebras de DNA de Cadeia Dupla , Meiose/genética , Animais , Cromossomos/genética , Quinase 2 Dependente de Ciclina/genética , Dano ao DNA/genética , Reparo do DNA/genética , Feminino , Recombinação Homóloga/genética , Masculino , Camundongos
18.
PLoS Genet ; 16(6): e1008894, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32598340

RESUMO

Meiotic crossovers (COs) are important for reshuffling genetic information between homologous chromosomes and they are essential for their correct segregation. COs are unevenly distributed along chromosomes and the underlying mechanisms controlling CO localization are not well understood. We previously showed that meiotic COs are mis-localized in the absence of AXR1, an enzyme involved in the neddylation/rubylation protein modification pathway in Arabidopsis thaliana. Here, we report that in axr1-/-, male meiocytes show a strong defect in chromosome pairing whereas the formation of the telomere bouquet is not affected. COs are also redistributed towards subtelomeric chromosomal ends where they frequently form clusters, in contrast to large central regions depleted in recombination. The CO suppressed regions correlate with DNA hypermethylation of transposable elements (TEs) in the CHH context in axr1-/- meiocytes. Through examining somatic methylomes, we found axr1-/- affects DNA methylation in a plant, causing hypermethylation in all sequence contexts (CG, CHG and CHH) in TEs. Impairment of the main pathways involved in DNA methylation is epistatic over axr1-/- for DNA methylation in somatic cells but does not restore regular chromosome segregation during meiosis. Collectively, our findings reveal that the neddylation pathway not only regulates hormonal perception and CO distribution but is also, directly or indirectly, a major limiting pathway of TE DNA methylation in somatic cells.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Cromossomos de Plantas/genética , Metilação de DNA , Meiose/genética , Proteínas de Arabidopsis/genética , Pareamento Cromossômico , Segregação de Cromossomos , Troca Genética , Quebras de DNA de Cadeia Dupla , Elementos de DNA Transponíveis/genética , Técnicas de Inativação de Genes , Plantas Geneticamente Modificadas
19.
Genes Dev ; 34(11-12): 731-732, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32482713

RESUMO

The exchange of genetic information between parental chromosomes in meiosis is an integral process for the creation of gametes. To generate a crossover, hundreds of DNA double-strand breaks (DSBs) are introduced in the genome of each meiotic cell by the SPO11 protein. The nucleolytic resection of DSB-adjacent DNA is a key step in meiotic DSB repair, but this process has remained understudied. In this issue of Genes & Development, Yamada and colleagues (pp. 806-818) capture some of the first details of resection and DSB repair intermediates in mouse meiosis using a method that maps blunt-ended DNA after ssDNA digestion. This yields some of the first genome-wide insights into DSB resection and repair in a mammalian genome and offers a tantalizing glimpse of how to quantitatively dissect this difficult to study, yet integral, nuclear process.


Assuntos
Quebras de DNA de Cadeia Dupla , Reparo do DNA/fisiologia , Meiose , Animais , Cromatina/química , Cromatina/metabolismo , DNA/química , Meiose/genética , Estrutura Molecular , Recombinação Genética
20.
Nature ; 582(7810): 124-128, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32494071

RESUMO

In most species, homologous chromosomes must recombine in order to segregate accurately during meiosis1. Because small chromosomes would be at risk of missegregation if recombination were randomly distributed, the double-strand breaks (DSBs) that initiate recombination are not located arbitrarily2. How the nonrandomness of DSB distributions is controlled is not understood, although several pathways are known to regulate the timing, location and number of DSBs. Meiotic DSBs are generated by Spo11 and accessory DSB proteins, including Rec114 and Mer2, which assemble on chromosomes3-7 and are nearly universal in eukaryotes8-11. Here we demonstrate how Saccharomyces cerevisiae integrates multiple temporally distinct pathways to regulate the binding of Rec114 and Mer2 to chromosomes, thereby controlling the duration of a DSB-competent state. The engagement of homologous chromosomes with each other regulates the dissociation of Rec114 and Mer2 later in prophase I, whereas the timing of replication and the proximity to centromeres or telomeres influence the accumulation of Rec114 and Mer2 early in prophase I. Another early mechanism enhances the binding of Rec114 and Mer2 specifically on the shortest chromosomes, and is subject to selection pressure to maintain the hyperrecombinogenic properties of these chromosomes. Thus, the karyotype of an organism and its risk of meiotic missegregation influence the shape and evolution of its recombination landscape. Our results provide a cohesive view of a multifaceted and evolutionarily constrained system that allocates DSBs to all pairs of homologous chromosomes.


Assuntos
Cromossomos Fúngicos/genética , Recombinação Homóloga , Meiose , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/genética , Centrômero/genética , Segregação de Cromossomos , Cromossomos Fúngicos/metabolismo , Quebras de DNA de Cadeia Dupla , Período de Replicação do DNA , Meiose/genética , Prófase Meiótica I/genética , Recombinases/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Telômero/genética , Fatores de Tempo
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