Characterization of molecular changes at meiotic initiation in mice
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE115928 | GEO | 2019/02/26
REPOSITORIES: GEO
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Project description:In mammalian testes, premeiotic spermatogonia respond to retinoic
acid by completing an essential lengthy differentiation program before
initiating meiosis. The molecular and cellular changes directing these
developmental processes remain largely undefined. This wide gap in
knowledge is due to two critical unresolved technical challenges: (1)
lack of robust and reliable in vitro models to study differentiation and
meiotic initiation; and (2) lack of methods to isolate large and pure
populations of male germ cells at each stage of differentiation and at
meiotic initiation. Here, we report a facile in vitro differentiation and
meiotic initiation system that can be readily manipulated, including the
use of chemical agents that cannot be safely administered to live
animals. In addition, we present a transgenic mouse model enabling
fluorescence-activated cell sorting-based isolation of millions of
spermatogonia at specific developmental stages as well as meiotic
spermatocytes
2022-10-28 | PXD037781 | JPOST Repository
Project description:Meiosis is a specialized form of cell division essential for sexual reproduction. The unique cellular events of meiosis have been extensively studied in model eukaryotes, including mammals. In mammals, the molecular and cellular changes that germ cells must undergo to transition from mitotic spermatogonia to meiotic spermatocytes remain largely undefined. Retinoic acid (RA) has been proposed as the meiosis inducing substance (MIS) required for female and male meiotic initiation. However, evidence for this presumption is based on studies of fetal gonads – meiosis is initiated in fetal ovaries but suppressed in fetal testes. Critically, the requirement for RA in meiosis has never been formally tested because germ cell differentiation and meiotic initiation in the fetal ovary are temporally inseparable. Using the postnatal mouse testis, where differentiation and meiotic initiation are temporally distinct (8.6 days apart), we test the hypothesis that RA is dispensable for initiation and progression through meiosis. Complementary in vivo experimental models were designed to address the hypothesis. In the first, “RA-sufficient” (RA-suf) model, spermatogenesis was synchronized by administration of potent and selective RA synthesis inhibitor; as a result, testes contained only undifferentiated spermatogonia. Then, the inhibitor was discontinued, and mice were given a single dose of exogenous RA to initiate spermatogonial differentiation. Germ cells completed differentiation, entered and completed meiosis, and formed haploid gametes at predicted timepoints. In the second, “RA-deficient” (RA-def) model, mice were treated as above, except the inhibitor was administered continuously. The lack of testicular RA in this model was confirmed in multiple ways, including assessment of RA-responsive gene expression, in vitro serum-free cultures, and dose-response experiments. To our surprise, germ cells in RA-def testes completed differentiation, underwent meiotic DNA replication, completed the landmark cytological processes of meiosis, and formed postmeiotic haploid spermatids, all on the predicted timeline of the RA-suf model. To define the effect of RA-deficiency on gene expression during meiotic initiation, large, highly enriched populations of premeiotic spermatogonia from RA-suf mice, and meiotic preleptotene spermatocytes from both models were FACS-isolated and subjected to bulk RNA-seq. Interestingly, analyses revealed few significant differences in expression of characteristic meiotic genes at the mRNA level. However, genes that were significantly different between RA-suf and RA-def preleptotene spermatocytes were associated with spermiogenesis functions. Taken together, our data reveal that, after initiating spermatogonial differentiation, RA is dispensable for initiation, progression through, and completion of meiosis in the male germline.
2023-07-03 | GSE194376 | GEO
Project description:Ray2013 - Meiotic initiation in S. cerevisiae
A mathematical representation of early meiotic events, particularly feedback mechanisms at the system level and phosphorylation of signalling molecules for regulating protein activities, is described here
This model is described in the article:
Dynamic modeling of yeast meiotic initiation.
Ray D, Su Y, Ye P.
BMC Syst Biol. 2013 May 1;7:37
Abstract:
BACKGROUND:
Meiosis is the sexual reproduction process common to eukaryotes. The diploid yeast Saccharomyces cerevisiae undergoes meiosis in sporulation medium to form four haploid spores. Initiation of the process is tightly controlled by intricate networks of positive and negative feedback loops. Intriguingly, expression of early meiotic proteins occurs within a narrow time window. Further, sporulation efficiency is strikingly different for yeast strains with distinct mutations or genetic backgrounds. To investigate signal transduction pathways that regulate transient protein expression and sporulation efficiency, we develop a mathematical model using ordinary differential equations. The model describes early meiotic events, particularly feedback mechanisms at the system level and phosphorylation of signaling molecules for regulating protein activities.
RESULTS:
The mathematical model is capable of simulating the orderly and transient dynamics of meiotic proteins including Ime1, the master regulator of meiotic initiation, and Ime2, a kinase encoded by an early gene. The model is validated by quantitative sporulation phenotypes of single-gene knockouts. Thus, we can use the model to make novel predictions on the cooperation between proteins in the signaling pathway. Virtual perturbations on feedback loops suggest that both positive and negative feedback loops are required to terminate expression of early meiotic proteins. Bifurcation analyses on feedback loops indicate that multiple feedback loops are coordinated to modulate sporulation efficiency. In particular, positive auto-regulation of Ime2 produces a bistable system with a normal meiotic state and a more efficient meiotic state.
CONCLUSIONS:
By systematically scanning through feedback loops in the mathematical model, we demonstrate that, in yeast, the decisions to terminate protein expression and to sporulate at different efficiencies stem from feedback signals toward the master regulator Ime1 and the early meiotic protein Ime2. We argue that the architecture of meiotic initiation pathway generates a robust mechanism that assures a rapid and complete transition into meiosis. This type of systems-level regulation is a commonly used mechanism controlling developmental programs in yeast and other organisms. Our mathematical model uncovers key regulations that can be manipulated to enhance sporulation efficiency, an important first step in the development of new strategies for producing gametes with high quality and quantity.
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2024-09-02 | BIOMD0000000626 | BioModels
Project description:In mammals, a key transition in spermatogenesis is the exit from spermatogonial differentiation and mitotic proliferation and the entry into spermatocyte differentiation and meiosis. Although several genes that regulate this transition have been identified, how it is controlled and coordinated remains poorly understood. Here we examine the role in male gametogenesis of the Doublesex-related gene Dmrt6 (Dmrtb1) and find that Dmrt6 plays a critical role in directing germ cells through the mitotic to meiotic germ cell transition. DMRT6 protein is expressed in late mitotic spermatogonia. In mice of the C57BL/6J strain a null mutation in Dmrt6 disrupts spermatogonial differentiation, causing expression in inappropriate cell types of spermatogonial differentiation factors including SOHLH1, SOHLH2 and DMRT1 and the meiotic initiation factor STRA8 and causing most late spermatogonia to undergo apoptosis. In mice of the 129Sv background, most Dmrt6 mutant spermatogonia can complete differentiation and enter meiosis, but they show defects in chromosome pairing, establishment of the XY body, and processing of recombination foci, and mainly arrest in mid-pachynema. mRNA profiling of Dmrt6 mutant testes together with DMRT6 ChIP-seq suggest that DMRT6 represses genes involved in spermatogonial differentiation and activates genes required for meiotic prophase. Our results indicate that Dmrt6 plays a key role in coordinating the transition in gametogenic programs from spermatogonial differentiation and mitosis to spermatocyte development and meiosis. Six samples for RNA-Seq with three biological replicates in each group. Two samples for ChIP-Seq (one input and one ChIP).
2014-10-31 | E-GEOD-60440 | biostudies-arrayexpress
Project description:In mammals, a key transition in spermatogenesis is the exit from spermatogonial differentiation and mitotic proliferation and the entry into spermatocyte differentiation and meiosis. Although several genes that regulate this transition have been identified, how it is controlled and coordinated remains poorly understood. Here we examine the role in male gametogenesis of the Doublesex-related gene Dmrt6 (Dmrtb1) and find that Dmrt6 plays a critical role in directing germ cells through the mitotic to meiotic germ cell transition. DMRT6 protein is expressed in late mitotic spermatogonia. In mice of the C57BL/6J strain a null mutation in Dmrt6 disrupts spermatogonial differentiation, causing expression in inappropriate cell types of spermatogonial differentiation factors including SOHLH1, SOHLH2 and DMRT1 and the meiotic initiation factor STRA8 and causing most late spermatogonia to undergo apoptosis. In mice of the 129Sv background, most Dmrt6 mutant spermatogonia can complete differentiation and enter meiosis, but they show defects in chromosome pairing, establishment of the XY body, and processing of recombination foci, and mainly arrest in mid-pachynema. mRNA profiling of Dmrt6 mutant testes together with DMRT6 ChIP-seq suggest that DMRT6 represses genes involved in spermatogonial differentiation and activates genes required for meiotic prophase. Our results indicate that Dmrt6 plays a key role in coordinating the transition in gametogenic programs from spermatogonial differentiation and mitosis to spermatocyte development and meiosis.
2014-10-31 | GSE60440 | GEO
Project description:Male germ cell meiosis is essential for generating haploid spermatozoa in mice. Here, we investigate the essential role of DIS3 in male germ cell meiosis in mice. Conditional inactivation of DIS3 in spermatocytes with Stra8-cre transgenic mice have severely impaired meiotic progression, which results in defective meiosis and spermatogenesis. RNA-seq analysis reveals that Dis3 deficiency causes significant dysregulation of the expression of transcripts in mutant testes. Meiosis-associated genes are significantly decreased in the absence of DIS3. Therefore, we show that DIS3 ribonuclease plays a critical role in germ cell meiosis during spermatogenesis in mice.
2021-07-16 | GSE180197 | GEO
Project description:Nitrogen starvation drives meiosis in yeasts1, while retinoic acid (RA) is required for mammalian meiosis through the activation of its germline-specific target, stimulated by retinoic acid gene 8 (Stra8).Here, by using single-cell transcriptome analysis of wild-type and Stra8-deficient testes, our data revealed that the expression of major metabolic genes are downregulated during germ cell entry into meiosis. Recently, we collected mouse testicular cells from wild-type and Stra8-deficient mice at postnatal day 12 (P12) and P21 for single cell RNA-sequencing (scRNA-seq). Upon scRNA-seq, we obtained a total of 23,470 cells from these samples. Using stringent quality control, 22,839 cells were selected for further analysis. All cells, including both wild-type and Stra8-deficient testicular cells, were pooled together to perform clustering analysis, which revealed 6 major cell clusters based on their distinct gene expression patterns. We annotated these six clusters by using known marker genes, including spermatogonia (SPG; Stra8; 3,941 cells), spermatocyte (SPC; Syce1; 4,924 cells), spermatid (STD; Acrv1; 710 cells), Sertoli cell (SC; Sox9; 9,488 cells), Myeloid (MYD; Acta2; 3,531 cells), and Leydig Cells (LY; Star; 245 cells). There is an increase in the percentage of spermatogonia in Stra8-deficient testes at both P12 (28% versus 14% in wild-type) and P21 (17% versus 10% in wild-type). At P21, while spermatocytes are abundant and spermatid are formed in wild-type testes, there are only a few spermatocytes (0.2% versus 73% in wild-type), and spermatids are absent in Stra8-deficient testes. Signature genes are enriched for GO terms for distinct biological function and metabolic pathways in different cell types.
2023-10-03 | GSE211390 | GEO
Project description:Male germ cell meiosis is essential for generating haploid spermatozoa in mice. Here, we investigate the essential role of DIS3L2 in male germ cell meiosis in mice. Conditional inactivation of DIS3L2 in spermatocytes with Stra8-cre transgenic mice have severely impaired meiotic progression, which results in defective meosis and spermatogenesis associated with a Sertoli cell-only syndrome and adult sterility. RNA-seq analysis reveales that Dis3l2 deficiency causes significant dysregulation of the expression of transcripts in mutant testes. Meiosis-assocaited genes are significantly decreased in the absence of DIS3L2. Therefore, we show that DIS3L2 ribonuclease plays a critical role in germ cell meiosis during spermatogenesis in mice.
2021-07-15 | GSE175883 | GEO
Project description:Male germ cells establish a unique heterochromatin domain, the XY-body, early in meiosis. How this domain is maintained through the end of meiosis and into post-meiotic germ cell differentiation is poorly understood. ADAD2 is a late meiotic male germ cell specific RNA binding protein, loss of which leads to post-meiotic germ cell defects. Analysis of ribosome association in Adad2 mutants revealed defective translation of Mdc1, a key regulator of XY-body formation, late in meiosis. As a result, Adad2 mutants show normal establishment but failed maintenance of the XY-body. Observed XY-body defects are concurrent with abnormal autosomal heterochromatin and ultimately lead to severely perturbed post-meiotic germ cell heterochromatin and cell death. These findings highlight the requirement of ADAD2 for Mdc1 translation, the role of MDC1 in maintaining meiotic male germ cell heterochromatin, and the importance of late meiotic heterochromatin for normal post-meiotic germ cell differentiation.
2021-12-11 | GSE190525 | GEO
Project description:The meiosis-specific chromosomal events of homolog pairing, synapsis, and recombination occur over an extended meiotic prophase I. In this study, we show that, in mice, maintenance of an extended meiotic prophase I requires the gene Meioc, a germ-cell specific factor conserved in most metazoans. Using immunoprecipitation and quantitative mass spectrometry, we identify proteins that interact with MEIOC in the mouse germ line.
2017-03-27 | PXD005473 | Pride