Bisection of the X Chromosome Disrupts the Initiation of Chromosome Silencing during Meiosis in Caenorhabditis elegans
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ABSTRACT:
ORGANISM(S): Caenorhabditis elegans
PROVIDER: GSE171938 | GEO | 2021/05/24
REPOSITORIES: GEO
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Project description:Balanced constitutional reciprocal translocations are the most common structural chromosomal rearrangements identified in man and pigs. Carriers are generally phenotypically normal, but such rearrangements frequently lead to reproductive disorders. In reciprocal translocation heterozygotes, the homologous regions of the normal and derivative chromosomes involved in the rearrangement pair during the prophase of the first meiotic division, thanks to the synaptonemal complex (SC), and form a particular structure called quadrivalent. In some cases, chromosomal regions (within the quadrivalent) remain unsynapsed, especially around the breakpoints, which may trigger meiosis checkpoints leading to spermatogenesis arrest at the pachytene stage. Several hypotheses have been proposed to explain such effects of pairing failure on gametogenesis. The first one is an altered transcription of the genes located on the unpaired segments. Indeed, studies conducted in mice revealed a transcriptional repression of unpaired regions by a specific mechanism called “Meiotic Silencing of Unsynapsed Chromatin” (MSUC) in individuals with a partial or total spermatogenesis arrest (Turner et al., 2005). If some genes necessary for the proper course of meiosis are located in such unsynapsed genomic regions, MSUC may result in an arrest of the meiotic division. Secondly, associations between the “quadrivalent” and the XY bivalent which is transcriptionally silenced by a phenomenon known as meiotic sex chromosome inactivation (MSCI, (Turner, 2007) were also observed in individuals with altered semen parameters (azoospermic or oligospemic) (Oliver-Bonet et al., 2005; Sciurano et al., 2007a, 2012). Such an association could result in a partial reactivation of the XY body (XYB) leading to the expression of some genes located on the X chromosome (Lifschytz and Lindsley, 1972), or result in the spreading of the XYB inactivation towards the autosomal segments attached to the XYB, without reactivation of the latter (Jaafar et al., 1993). Beyond the potential spermatogenesis failure mentioned above, reciprocal translocations are systematically responsible for the production of genetically unbalanced gametes. Here we report the detailed analysis of the whole meiotic process (from spermatocytes to spermatozoa) in the case of a constitutional balanced reciprocal translocation responsible for severe oligoasthenoteratospermia.
2016-06-30 | GSE80693 | GEO
Project description:Balanced constitutional reciprocal translocations are the most common structural chromosomal rearrangements identiï¬ed in man and pigs. Carriers are generally phenotypically normal, but such rearrangements frequently lead to reproductive disorders. In reciprocal translocation heterozygotes, the homologous regions of the normal and derivative chromosomes involved in the rearrangement pair during the prophase of the first meiotic division, thanks to the synaptonemal complex (SC), and form a particular structure called quadrivalent. In some cases, chromosomal regions (within the quadrivalent) remain unsynapsed, especially around the breakpoints, which may trigger meiosis checkpoints leading to spermatogenesis arrest at the pachytene stage. Several hypotheses have been proposed to explain such effects of pairing failure on gametogenesis. The first one is an altered transcription of the genes located on the unpaired segments. Indeed, studies conducted in mice revealed a transcriptional repression of unpaired regions by a specific mechanism called âMeiotic Silencing of Unsynapsed Chromatinâ (MSUC) in individuals with a partial or total spermatogenesis arrest (Turner et al., 2005). If some genes necessary for the proper course of meiosis are located in such unsynapsed genomic regions, MSUC may result in an arrest of the meiotic division. Secondly, associations between the âquadrivalentâ and the XY bivalent which is transcriptionally silenced by a phenomenon known as meiotic sex chromosome inactivation (MSCI, (Turner, 2007) were also observed in individuals with altered semen parameters (azoospermic or oligospemic) (Oliver-Bonet et al., 2005; Sciurano et al., 2007a, 2012). Such an association could result in a partial reactivation of the XY body (XYB) leading to the expression of some genes located on the X chromosome (Lifschytz and Lindsley, 1972), or result in the spreading of the XYB inactivation towards the autosomal segments attached to the XYB, without reactivation of the latter (Jaafar et al., 1993). Beyond the potential spermatogenesis failure mentioned above, reciprocal translocations are systematically responsible for the production of genetically unbalanced gametes. Here we report the detailed analysis of the whole meiotic process (from spermatocytes to spermatozoa) in the case of a constitutional balanced reciprocal translocation responsible for severe oligoasthenoteratospermia. Total RNA was extracted in 3 replicates from testicular biopsies control animals, from testicular biopsy of an oligospermic boar and from testicular biopsy of a severe oligo-astheno-teratospermic boar carrier of the trcp(1;14) reciprocal translocation.
2016-06-30 | E-GEOD-80693 | biostudies-arrayexpress
Project description:Transfer of genetic traits from wild or related species into cultivated rice is nowadays an important aim in rice breeding. Breeders use genetic crosses to introduce desirable genes from exotic germplasms into cultivated rice varieties. However, in many hybrids there is only a low level of pairing (if existing) and recombination at early meiosis between cultivated rice and wild relative chromosomes. With the objective of getting deeper into the knowledge of the proteins involved in early meiosis, when chromosomes associate correctly in pairs and recombine, the proteome of isolated rice meiocytes has been characterized by nLC-MS/MS at every stage of early meiosis (prophase I). Up to 1316 different proteins have been identified in rice isolated meiocytes in early meiosis, being 422 exclusively identified in early prophase I (leptotene, zygotene or pachytene). The classification of proteins in functional groups showed that 167 were related to chromatin structure and remodelling, nucleic acid binding, cell-cycle regulation and cytoskeleton. Moreover, the putative roles of sixteen proteins which have not been previously associated to meiosis or were not identified in rice before, are also discussed namely: seven proteins involved in chromosome structure and remodeling, five regulatory proteins (such as SKP1 (OSK), a putative CDK2 like efector), a protein with RNA recognition motifs, a neddylation-related protein, and two microtubule-related proteins. Revealing the proteins involved in early meiotic processes could provide a valuable tool kit to manipulate chromosome associations during meiosis in rice breeding programs.
2014-08-13 | PXD001058 | Pride
Project description:In mammals and several other taxa, the ability of males to cope with the limited synapsis of the X and Y chromosomes during prophase I of meiosis relies on the process of meiotic sex chromosome inactivation (MSCI). Components of the somatic DNA damage response machinery, including ATR, TOPBP1, MDC1 and BRCA1 play key roles in MSCI, although how they establish XY silencing remains incompletely understood. In particular, it remains unclear how DDR factors coordinate XY silencing with DNA repair, chromosome synapsis and the formation of the sex body, a distinct phase-separated sub-nuclear structure formed during prophase I to house the unsynapsed XY bivalent. Here we report a mutant mouse (Topbp1B5/B5), harboring mutations in the BRCT5 domain of Topbp1, that shows impaired XY silencing but grossly normal sex body formation. While Topbp1B5/B5 mice are viable, without detectable somatic defects, males are completely infertile. Distinct from mice lacking ATR or TOPBP1 specifically during meiosis, Topbp1B5/B5 males exhibit normal chromosome synapsis and canonical markers of DNA repair in early prophase I. ATR signaling is mostly intact in Topbp1B5/B5 spermatocytes, although specific ATR-dependent events are disrupted, including localization of the RNA:DNA helicase Senataxin to chromatin loops of the XY. Strikingly, while Topbp1B5/B5 spermatocytes are able to initiate MSCI the completion of gene silencing is defective, with a subset of X chromosome genes displaying distinct patterns of transcriptional deregulation. These findings suggest a non-canonical role for the ATR-TOPBP1 signaling axis in XY silencing dynamics at advanced stages in pachynema. This is the first DDR mutant that separates XY silencing from sex body formation, as well as TOPBP1’s role in spermatogenesis from its roles in organismal viability.
2024-02-09 | PXD042199 | Pride
Project description:Meiosis produces gametes through a specialised, two-step cell division, which is highly error-prone in humans. Reductional meiosis I, where maternal and paternal chromosomes (homologs) segregate, is followed by equational meiosis II, where sister chromatids separate. Uniquely during meiosis I, sister kinetochores are monooriented and pericentromeric cohesin is protected. Here, we demonstrate that these key adaptations for reductional chromosome segregation are achieved through separable control of multiple kinases by the meiosis I-specific budding yeast Spo13 protein. Recruitment of Polo kinase to kinetochores directs monoorientation, while, independently, cohesin protection is achieved by controlling the effects of cohesin kinases. Therefore, reductional chromosome segregation, the defining feature of meiosis, is established by multifaceted kinase control by a master regulator. The recent identification of Spo13 orthologs, fission yeast Moa1 and mouse MEIKIN, suggests that kinase coordination by a master meiosis I regulator may be a general feature in the establishment of reductional chromosome segregation.
2019-11-13 | PXD012627 | Pride
Project description:Meiotic sex chromosome inactivation (MSCI) is an essential event in meiotic progression in mammalian spermatogenesis. We found that La Ribonucleoprotein 7 (LARP7) is involved in MSCI. LARP7 plays a role in fetal germ cells to promote their proliferation, but is once abolished in postnatal gonocytes and re-expresses in spermatocytes at the onset of meiosis. In spermatocytes, LARP7 localizes to the XY body, a compartmentalized chromatin domain on sex chromosomes. This study aimed to elucidate a possible function of LARP7 in the XY body by using germline-specific Larp7-deficient mice.
2024-10-01 | GSE261526 | GEO
Project description:Meiosis is a highly complex process that underpins recombination in sexually reproducing organisms. Recent genomics studies suggest that up to several thousand genes/proteins contribute to the meiotic pathway, yet relatively few have been functionally characterised. Our understanding of the physical interactions between meiotic proteins and how the meiotic machinery interacts with other components of the cell is also limited. In this study, we used affinity proteomics targeting the meiotic chromosome axis protein, ASY1, to enrich for axis-associated proteins in Brassica oleracea anthers or meiocytes in prophase I of meiosis. LC-MS/MS analysis identified 540 proteins which co-immunoprecipitated with ASY1 in a sample-specific manner. These correspond to 485 Arabidopsis orthologues, 90% of which form a coherent predicted protein-protein interaction network which includes known and novel meiotic proteins, based on mutant analysis, but also proteins more usually associated with other cellular processes including replication and proteolysis. Our data provided new insights into the role of the chromosome axis in plant meiosis. We identified a novel axis-associated protein and showed that during prophase I, ASY1 and its interacting partner, ASY3, are extensively phosphorylated. Further studies targeting other meiotic proteins may ultimately enable the construction of a comprehensive meiosis protein-protein interaction network for higher plants.
2017-11-01 | PXD006042 | Pride
Project description:In mammals, homologous chromosomes rarely pair outside meiosis. One exception is the X chromosome, which transiently pairs during X-chromosome inactivation (XCI). How two chromosomes find each other in 3D space is not known. Here, we reveal a required interaction between the X-inactivation center (Xic) and the telomere in mouse embryonic stem (ES) cells. The subtelomeric, pseudoautosomal regions (PARs) of the two sex chromosomes (X and Y) also undergo pairing in both female and male cells. PARs transcribe a class of telomeric RNA, dubbed PAR-TERRA, which accounts for a vast majority of all TERRA transcripts. PAR-TERRA binds throughout the genome, including to the PAR and Xic. During X-chromosome pairing, PAR-TERRA anchors the Xic to the PAR, creating a ‘tetrad’ of pairwise homologous interactions (Xic–Xic, PAR–PAR, and Xic–PAR). Xic pairing occurs within the tetrad. Depleting PAR-TERRA abrogates pairing and blocks initiation of XCI, whereas autosomal PAR-TERRA induces ectopic pairing. We propose a ‘constrained diffusion model’ in which PAR-TERRA creates an interaction hub to guide Xic homology searching during XCI.
2017-07-10 | GSE69887 | GEO
Project description:During meiosis, a single round of DNA replication is followed by two consecutive rounds of nuclear divisions called meiosis I and meiosis II. In meiosis I, homologous chromosomes segregate, while sister chromatids remain together. Determining how this unusual chromosome segregation behavior is established is central to understanding germ cell development. Here we show that preventing microtubule-kinetochore interactions during premeiotic S phase and prophase I is essential for establishing the meiosis I chromosome segregation pattern. Premature interactions of kinetochores with microtubules transform meiosis I into a mitosis-like division by disrupting two key meiosis I events: coorientation of sister kinetochores and protection of centromeric cohesin removal from chromosomes. Furthermore we find that restricting outer kinetochore assembly contributes to preventing premature engagement of microtubules with kinetochores. We propose that inhibition of microtubule-kinetochore interactions during premeiotic S phase and prophase I is central to establishing the unique meiosis I chromosome segregation pattern.
2012-10-05 | GSE41339 | GEO
Project description:It is well recognized that men and women differ in circulating lipid profiles and consequently coronary artery disease (CAD). While sex hormones like estrogens are thought to protect women from CAD risk by promoting protective lipid profiles, hormone replacement therapy in women paradoxically increases CAD risk. Biological sex is determined by both sex chromosomes and sex hormones. We used mouse models to separate effects of sex chromosomes and hormones on atherosclerosis, circulating lipids and intestinal fat metabolism. We found that an XX sex chromosome complement increases food intake, body weight, fat absorption, serum lipid concentrations and atherosclerosis in gonadal male and female mice, indicating a primary effect of sex chromosome complement. Small intestine expression of enzymes involved in lipid absorption and chylomicron assembly were increased in XX male and female mice with elevated intestinal lipids. These results reveal that an XX sex chromosome complement promotes the absorption and bioavailability of dietary fat to accelerate the development of atherosclerosis.
2019-04-17 | GSE119497 | GEO