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BioRxiv : the Preprint Server For... May 2024Double-strand breaks (DSBs) are the most deleterious lesions experienced by our genome. Yet, DSBs are intentionally induced during gamete formation to promote the...
Double-strand breaks (DSBs) are the most deleterious lesions experienced by our genome. Yet, DSBs are intentionally induced during gamete formation to promote the exchange of genetic material between homologous chromosomes. While the conserved topoisomerase-like enzyme Spo11 catalyzes DSBs, additional regulatory proteins-referred to as "Spo11 accessory factors"- regulate the number, timing, and placement of DSBs during early meiotic prophase ensuring that SPO11 does not wreak havoc on the genome. Despite the importance of the accessory factors, they are poorly conserved at the sequence level suggesting that these factors may adopt unique functions in different species. In this work, we present a detailed analysis of the genetic and physical interactions between the DSB factors in the nematode providing new insights into conserved and novel functions of these proteins. This work shows that HIM-5 is the determinant of X-chromosome-specific crossovers and that its retention in the nucleus is dependent on DSB-1, the sole accessory factor that interacts with SPO-11. We further provide evidence that HIM-5 coordinates the actions of the different accessory factors sub-groups, providing insights into how components on the DNA loops may interact with the chromosome axis.
PubMed: 38463951
DOI: 10.1101/2024.02.23.581796 -
PLoS Genetics Mar 2024During meiosis, genetic recombination is initiated by the formation of many DNA double-strand breaks (DSBs) catalysed by the evolutionarily conserved topoisomerase-like...
During meiosis, genetic recombination is initiated by the formation of many DNA double-strand breaks (DSBs) catalysed by the evolutionarily conserved topoisomerase-like enzyme, Spo11, in preferred genomic sites known as hotspots. DSB formation activates the Tel1/ATM DNA damage responsive (DDR) kinase, locally inhibiting Spo11 activity in adjacent hotspots via a process known as DSB interference. Intriguingly, in S. cerevisiae, over short genomic distances (<15 kb), Spo11 activity displays characteristics of concerted activity or clustering, wherein the frequency of DSB formation in adjacent hotspots is greater than expected by chance. We have proposed that clustering is caused by a limited number of sub-chromosomal domains becoming primed for DSB formation. Here, we provide evidence that DSB clustering is abolished when meiotic prophase timing is extended via deletion of the NDT80 transcription factor. We propose that extension of meiotic prophase enables most cells, and therefore most chromosomal domains within them, to reach an equilibrium state of similar Spo11-DSB potential, reducing the impact that priming has on estimates of coincident DSB formation. Consistent with this view, when Tel1 is absent but Ndt80 is present and thus cells are able to rapidly exit meiotic prophase, genome-wide maps of Spo11-DSB formation are skewed towards pericentromeric regions and regions that load pro-DSB factors early-revealing regions of preferential priming-but this effect is abolished when NDT80 is deleted. Our work highlights how the stochastic nature of Spo11-DSB formation in individual cells within the limited temporal window of meiotic prophase can cause localised DSB clustering-a phenomenon that is exacerbated in tel1Δ cells due to the dual roles that Tel1 has in DSB interference and meiotic prophase checkpoint control.
Topics: DNA; DNA Breaks, Double-Stranded; DNA-Binding Proteins; Endodeoxyribonucleases; Intracellular Signaling Peptides and Proteins; Meiosis; Prophase; Protein Serine-Threonine Kinases; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins
PubMed: 38427688
DOI: 10.1371/journal.pgen.1011140 -
Nucleic Acids Research May 2024Accurate chromosome segregation during meiosis requires the establishment of at least one crossover (CO) between each pair of homologous chromosomes. CO formation...
Accurate chromosome segregation during meiosis requires the establishment of at least one crossover (CO) between each pair of homologous chromosomes. CO formation depends on a group of conserved pro-CO proteins, which colocalize at CO-designated sites during late meiotic prophase I. However, it remains unclear whether these pro-CO proteins form a functional complex and how they promote meiotic CO formation in vivo. Here, we show that COSA-1, a key component required for CO formation, interacts with other pro-CO factors, MSH-5 and ZHP-3, via its N-terminal disordered region. Point mutations that impair these interactions do not affect CO designation, but they strongly hinder the accumulation of COSA-1 at CO-designated sites and result in defective CO formation. These defects can be partially bypassed by artificially tethering an interaction-compromised COSA-1 derivate to ZHP-3. Furthermore, we revealed that the accumulation of COSA-1 into distinct foci is required to assemble functional 'recombination nodules'. These prevent early CO-designated recombination intermediates from being dismantled by the RTEL-1 helicase and protect late recombination intermediates, such as Holliday junctions, until they are resolved by CO-specific resolvases. Altogether, our findings provide insight into COSA-1 mediated pro-CO complex assembly and its contribution to CO formation.
Topics: Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Chromosome Segregation; Crossing Over, Genetic; DNA-Binding Proteins; Meiosis
PubMed: 38412290
DOI: 10.1093/nar/gkae130 -
Molecular Genetics & Genomic Medicine Feb 2024Recurrent miscarriage (RM) affects 1% to 5% of couples trying to conceive. Despite extensive clinical and laboratory testing, half of the RM cases remain unexplained. We...
BACKGROUND
Recurrent miscarriage (RM) affects 1% to 5% of couples trying to conceive. Despite extensive clinical and laboratory testing, half of the RM cases remain unexplained. We report the genetic analysis of a couple with eight miscarriages and the search for their potential genetic etiology.
METHODS
Short tandem repeat (STR) markers, single nucleotide polymorphic (SNP) microarray, and human DNA methylation microarray were used to analyze the genotypes of two miscarriages. Exomes sequencing was performed on DNA from the two partners and identified variants were validated by Sanger sequencing.
RESULTS
STR marker genotyping demonstrated that the two available miscarriages are triploid digynic and resulted from the failure of Meiosis II. SNP microarray analysis revealed an additional Meiosis I abnormality that is the segregation of the two maternal homologous chromosomes in one triploid miscarriage. Whole-exome sequencing on DNA from the two partners identified candidate variants only in the female partner in two genes with roles in female reproduction, a missense in EIF4ENIF1 (OMIM 607445) and a stop gain in HORMAD2 (OMIM 618842). EIF4ENIF1 is a eukaryotic translation initiation factor 4E nuclear import factor required for the oocyte germinal vesicle breakdown, and HORMAD2 is part of the synaptonemal complex that was hypothesized to act as a checkpoint mechanism to eliminate oocytes with asynapsis during meiotic prophase I in mice.
CONCLUSION
While both genes may contribute to the phenotype, the Meiosis I abnormalities in the conceptions favor the causal role of HORMAD2 in the etiology of RM in this couple. This report illustrates the importance of comprehensively analyzing the products of conception to guide the search for the genetic causation of RM.
Topics: Female; Humans; Pregnancy; Abortion, Habitual; Codon, Terminator; DNA; Meiosis; Triploidy; Male
PubMed: 38400599
DOI: 10.1002/mgg3.2402 -
ELife Feb 2024Meiotic sex chromosome inactivation (MSCI) is a critical feature of meiotic prophase I progression in males. While the ATR kinase and its activator TOPBP1 are key...
Meiotic sex chromosome inactivation (MSCI) is a critical feature of meiotic prophase I progression in males. While the ATR kinase and its activator TOPBP1 are key drivers of MSCI within the specialized sex body (SB) domain of the nucleus, how they promote silencing remains unclear given their multifaceted meiotic functions that also include DNA repair, chromosome synapsis, and SB formation. Here we report a novel mutant mouse harboring mutations in the TOPBP1-BRCT5 domain. males are infertile, with impaired MSCI despite displaying grossly normal events of early prophase I, including synapsis and SB formation. Specific ATR-dependent events are disrupted, including phosphorylation and localization of the RNA:DNA helicase Senataxin. spermatocytes initiate, but cannot maintain ongoing, MSCI. These findings reveal a non-canonical role for the ATR-TOPBP1 signaling axis in MSCI dynamics at advanced stages in pachynema and establish the first mouse mutant that separates ATR signaling and MSCI from SB formation.
Topics: Animals; Humans; Male; Mice; Alleles; Carrier Proteins; DNA Repair; DNA-Binding Proteins; Infertility, Male; Meiosis; Nuclear Proteins; Sex Chromosomes
PubMed: 38391183
DOI: 10.7554/eLife.90887 -
BMJ Mental Health Feb 2024Increasing data suggest emergent affective symptoms during the COVID-19 pandemic.
BACKGROUND
Increasing data suggest emergent affective symptoms during the COVID-19 pandemic.
OBJECTIVES
To study the impact of the COVID-19 pandemic on affective symptoms and suicidal ideation in Thai adults.
METHODS
The Collaborative Outcomes Study on Health and Functioning during Infection Times uses non-probability sampling (chain referring and voluntary response sampling) and stratified probability sampling to identify risk factors of mental health problems and potential treatment targets to improve mental health outcomes during pandemics.
FINDINGS
Analysing 14 271 adult survey participants across all four waves of the COVID-19 pandemic in Thailand, covering all 77 provinces from 1 June 2020 to 30 April 2022, affective symptoms and suicidality increased during COVID-19 pandemic. Affective symptoms were strongly predicted by pandemic (feelings of isolation, fear of COVID-19, loss of social support, financial loss, lack of protective devices) and non-pandemic (female sex, non-binary individuals, adverse childhood experiences (ACEs), negative life events, student status, multiple mental health and medical conditions, physical pain) risk factors. ACEs, prior mental health conditions and physical pain were the top three risk factors associated with both increased affective symptoms and suicidal ideation during the COVID-19 pandemic. Partial least squares analysis showed that ACEs were the most important risk factor as they impacted most pandemic and non-pandemic risk factors.
CLINICAL IMPLICATIONS
Rational policymaking during a pandemic should aim to identify the groups at highest risk (those with ACEs, psychiatric and medical disease, women, non-binary individuals) and implement both immediate and long-term strategies to mitigate the impact of ACEs, while effectively addressing associated psychiatric and medical conditions.
Topics: Adult; Humans; Female; Suicidal Ideation; Affective Symptoms; Pandemics; Thailand; COVID-19; Pain
PubMed: 38379238
DOI: 10.1136/bmjment-2023-300982 -
PLoS Genetics Feb 2024Meiotic recombination between homologous chromosomes is initiated by the formation of hundreds of programmed double-strand breaks (DSBs). Approximately 10% of these DSBs...
Meiotic recombination between homologous chromosomes is initiated by the formation of hundreds of programmed double-strand breaks (DSBs). Approximately 10% of these DSBs result in crossovers (COs), sites of physical DNA exchange between homologs that are critical to correct chromosome segregation. Virtually all COs are formed by coordinated efforts of the MSH4/MSH5 and MLH1/MLH3 heterodimers, the latter representing the defining marks of CO sites. The regulation of CO number and position is poorly understood, but undoubtedly requires the coordinated action of multiple repair pathways. In a previous report, we found gene-trap disruption of the DNA helicase, FANCJ (BRIP1/BACH1), elicited elevated numbers of MLH1 foci and chiasmata. In somatic cells, FANCJ interacts with numerous DNA repair proteins including MLH1, and we hypothesized that FANCJ functions with MLH1 to regulate the major CO pathway. To further elucidate the meiotic function of FANCJ, we produced three new Fancj mutant mouse lines via CRISPR/Cas9 gene editing: a full-gene deletion, truncation of the N-terminal Helicase domain, and a C-terminal dual-tagged allele. We also generated an antibody against the C-terminus of the mouse FANCJ protein. Surprisingly, none of our Fancj mutants show any change in either MLH1 focus counts during pachynema or total CO number at diakinesis of prophase I. We find evidence that FANCJ and MLH1 do not interact in meiosis; further, FANCJ does not co-localize with MSH4, MLH1, or MLH3 in meiosis. Instead, FANCJ co-localizes with BRCA1 and TOPBP1, forming discrete foci along the chromosome cores beginning in early meiotic prophase I and densely localized to unsynapsed chromosome axes in late zygonema and to the XY chromosomes in early pachynema. Fancj mutants also exhibit a subtle persistence of DSBs in pachynema. Collectively, these data indicate a role for FANCJ in early DSB repair, but they rule out a role for FANCJ in MLH1-mediated CO events.
Topics: Animals; Male; Mice; Alleles; DNA Helicases; DNA Repair; Meiosis; Meiotic Prophase I
PubMed: 38377115
DOI: 10.1371/journal.pgen.1011175 -
Cell Reports Feb 2024Oocytes are arrested in prophase I. In vertebrates, meiotic resumption is triggered by hormonal stimulation that results in cAMP-dependent protein kinase (PKA)...
Oocytes are arrested in prophase I. In vertebrates, meiotic resumption is triggered by hormonal stimulation that results in cAMP-dependent protein kinase (PKA) downregulation leading to Cdk1 activation. Yet the pathways connecting PKA to Cdk1 remain unclear. Here, we identify molecular events triggered by PKA downregulation occurring upstream of Cdk1 activation. We describe a two-step regulation controlling cyclin B1 and Mos accumulation, which depends on both translation and stabilization. Cyclin B1 accumulation is triggered by PKA inhibition upstream of Cdk1 activation, while its translation requires Cdk1 activity. Conversely, Mos translation initiates in response to the hormone, but the protein accumulates only downstream of Cdk1. Furthermore, two successive translation waves take place, the first controlled by PKA inhibition and the second by Cdk1 activation. Notably, Arpp19, an essential PKA effector, does not regulate the early PKA-dependent events. This study elucidates how PKA downregulation orchestrates multiple pathways that converge toward Cdk1 activation and induce the oocyte G2/M transition.
Topics: Animals; Cyclin B1; Oocytes; Down-Regulation; Cell Growth Processes; Cyclic AMP-Dependent Protein Kinases
PubMed: 38358892
DOI: 10.1016/j.celrep.2024.113782 -
Science Advances Feb 2024The synaptonemal complex (SC) is a zipper-like protein assembly that links homologous chromosomes to regulate recombination and segregation during meiosis. The SC has...
The synaptonemal complex (SC) is a zipper-like protein assembly that links homologous chromosomes to regulate recombination and segregation during meiosis. The SC has been notoriously refractory to in vitro reconstitution, thus leaving its molecular organization largely unknown. Here, we report a moonlighting function of two paralogous S-phase kinase-associated protein 1 (Skp1)-related proteins (SKR-1 and SKR-2), well-known adaptors of the Skp1-Cul1-F-box (SCF) ubiquitin ligase, as the key missing components of the SC in . SKR proteins repurpose their SCF-forming interfaces to dimerize and interact with meiosis-specific SC proteins, thereby driving synapsis independent of SCF activity. SKR-1 enables the formation of the long-sought-after soluble complex with previously identified SC proteins in vitro, which we propose it to represent a complete SC building block. Our findings demonstrate how a conserved cell cycle regulator has been co-opted to interact with rapidly evolving meiotic proteins to construct the SC and provide a foundation for understanding its structure and assembly mechanisms.
Topics: Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Cell Cycle Proteins; S-Phase Kinase-Associated Proteins; Synaptonemal Complex
PubMed: 38354250
DOI: 10.1126/sciadv.adl4876 -
BioRxiv : the Preprint Server For... Apr 2024The classical phenomenon of crossover interference is a one-dimensional spatial patterning process that produces evenly spaced crossovers during meiosis. Quantitative...
The classical phenomenon of crossover interference is a one-dimensional spatial patterning process that produces evenly spaced crossovers during meiosis. Quantitative analysis of diagnostic molecules along budding yeast chromosomes reveals that this process also sets up a second, interdigitated pattern of related but longer periodicity, in a "two-tiered" patterning process. The second tier corresponds to a previously mysterious minority set of crossovers. Thus, in toto, the two tiers account for all detected crossover events. Both tiers of patterning set up spatially clustered assemblies of three types of molecules ("triads") representing the three major components of meiotic chromosomes (crossover recombination complexes and chromosome axis and synaptonemal complex components), and give focal and domainal signals, respectively. Roles are suggested. All observed effects are economically and synthetically explained if crossover patterning is mediated by mechanical forces along prophase chromosomes. Intensity levels of domainal triad components are further modulated, dynamically, by the conserved protein remodeler Pch2/TRIP13.
PubMed: 38352537
DOI: 10.1101/2024.01.28.577645