Meiotic Consequences of Genetic Extension of Unsynapsed Autosomal Chromatin
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE29177 | GEO | 2014/05/09
SECONDARY ACCESSION(S): PRJNA139985
REPOSITORIES: GEO
Similar Datasets
Project description:We investigated the influence of extension of autosomal asynapsis on expression profiles during spermatogenesis. We used the mouse autosomal translocation T(16;17)43H (abbreviated T43H) and t12 haplotype, a natural variant of Chr 17 encompassing four adjacent non-overlapping inversions proximal to the T43H translocation breakpoint, as a model. The presence of t12 haplotype in trans to the T43H translocation resulted in stringent spermatogenic block and in more complete silencing of genes surrounding the T43H translocation break. Strikingly, silencing of the unsynapsed autosomal chromatin preceded the inactivation of the sex chromosomes (MSCI) and was apparent already in the population of pre-mid pachytene spermatocytes and testes of 15 days old males. Populations of pre-mid-pachytene spermatocytes were isolated from Ttf+/+T43H and t12+/+T43 males in three biological replicates. Their expression was compared to two biological replicates of the populations of pre-mid pachytene spermatocytes and mid-late pachytene spermatocytes obtained from C57BL/10J fertile males. Independently, testicular RNA was isolated from 15 days old Ttf+/+T43H and t12+/+T43 males in three biological replicates and the expression was compared to the testicular expression of two 15 days old C57BL/6J males.
2014-05-09 | E-GEOD-29177 | biostudies-arrayexpress
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: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: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:Autosomal trisomies and monosomies bring serious threats to embryonic development through transcriptional disarray primarily caused by the dosage effect of the aneuploid part of the genome. The present study compared the effect of a mouse viable 30 Mb segmental trisomy on the genome-wide transcriptional profile of somatic (liver) cells and male germ cells. While the 1.6-fold change in expression of triplicated genes reflected the gene dosage in liver cells, the extra copy was almost fully compensated in early pachytene spermatocytes, showing 1.18-fold increase. Allele-specific semi-quantitative evaluation of steady-state mRNA levels of the triplicated Amdhd2 gene revealed silencing evenly distributed among all three copies in these meiotic cells. Although more pronounced, the dosage compensation of trisomic genes was concordant with the incidence of HORMAD2 and γH2AX markers of unsynapsed chromatin. The possible explanations include insufficient sensitivity to detect both MSUC markers in the 30 Mb region of the chromosome, or an early silencing effect of another epigenetic factor. Taken together, our results indicate that the meiotic silencing of unsynapsed chromatin is the major but not the only factor driving the dosage compensation of triplicated genes in primary spermatocytes.
2016-03-30 | GSE54683 | GEO
Project description:Characterization of the H3K9me2 distribution in the C. elegans adult hermaphrodite genome using ChIP-Seq Examination of H3K9me2 in two different nematode strains: fer-1 control and fer-1;him-8 mutant, where the X chromosomes are unsynapsed. The fer-1 mutation prevents production of embryos.
2015-09-04 | E-GEOD-67028 | biostudies-arrayexpress
Project description:Autosomal trisomies and monosomies bring serious threats to embryonic development through transcriptional disarray primarily caused by the dosage effect of the aneuploid part of the genome. The present study compared the effect of a mouse viable 30 Mb segmental trisomy on the genome-wide transcriptional profile of somatic (liver) cells and male germ cells. While the 1.6-fold change in expression of triplicated genes reflected the gene dosage in liver cells, the extra copy was almost fully compensated in early pachytene spermatocytes, showing 1.18-fold increase. Allele-specific semi-quantitative evaluation of steady-state mRNA levels of the triplicated Amdhd2 gene revealed silencing evenly distributed among all three copies in these meiotic cells. Although more pronounced, the dosage compensation of trisomic genes was concordant with the incidence of HORMAD2 and γH2AX markers of unsynapsed chromatin. The possible explanations include insufficient sensitivity to detect both MSUC markers in the 30 Mb region of the chromosome, or an early silencing effect of another epigenetic factor. Taken together, our results indicate that the meiotic silencing of unsynapsed chromatin is the major but not the only factor driving the dosage compensation of triplicated genes in primary spermatocytes. We compared the global expression profiles in isolated popoulations of meiotic cells and liver cells of Ts43H trisomic males and their t121/D17 euploid siblings.
2016-03-30 | E-GEOD-54683 | biostudies-arrayexpress
Project description:Meiotic Consequences of Genetic Extension of Unsynapsed Autosomal Chromatin
| PRJNA139985 | ENA
Project description:Meiotic sex chromosome inactivation (MSCI) is an essential process in the male germline. While genetic experiments have established that the DNA damage response (DDR) pathway directs MSCI, due to limitations to the experimental systems available, mechanisms underlying MSCI remain largely unknown. Here we establish a system to study MSCI ex vivo, based on a short-term culture method, and demonstrate that active DDR signaling is required both to initiate and maintain MSCI via a dynamic and reversible process. DDR-directed MSCI follows two layers of modifications: active DDR-dependent reversible processes and irreversible histone post-translational modifications. Further, the DDR initiates MSCI independent of the downstream repressive histone mark H3K9 trimethylation (H3K9me3), thereby demonstrating that active DDR signaling is the primary mechanism of silencing in MSCI. By unveiling the dynamic nature of MSCI, and its governance by active DDR signals, our study highlights the sex chromosomes as an active signaling hub in meiosis.
2022-10-05 | GSE211519 | GEO
Project description:The four mammalian Argonaute family members are thought to share redundant functions in the microRNA pathway, yet only AGO2 possesses the catalytic "slicer" function required for RNA interference. Whether AGO1, AGO3, or AGO4 possess specialized functions remains unclear. Here, we Series_summary = show that AGO4 localizes to spermatocyte nuclei during meiotic prophase I, specifically at sites of asynapsis and in the transcriptionally silenced XY sub-domain, the sex body. We generated Ago4 knockout mice and show that Ago4-/- spermatogonia initiate meiosis early, resulting from premature induction of retinoic acid-response genes. During prophase I, the sex body assembles incorrectly in Ago4-/- mice, leading to disrupted meiotic sex chromosome inactivation (MSCI). This is associated with a dramatic loss of microRNAs, >20% of which arise from the X chromosome. Loss of AGO4 results in increased AGO3 in spermatocytes, indicating some degree of redundancy. Thus, AGO4 regulates meiotic entry and MSCI in mammalian germ cells, implicating small RNA pathways in these processes. mRNA transcripts were isolated and prepared using pachytene spermatocytes, pre-meiotic testes and other tissues from Ago4+/+ and Ago4-/- littermates and sequenced using Illumina HiSeq2000. small RNA transcripts were isolated and prepared using pachytene spermatocytes from adult Ago4+/+ and Ago4-/- littermates and sequenced using Illumina GAII.
2012-08-01 | E-GEOD-39652 | biostudies-arrayexpress