Project description:During female reproductive life, the reserve of ovarian follicles is reduced by maturation and atresia until menopause ensues. Foxo3 is required to maintain the ovarian reserve in mice. We asked if overexpression of a constitutively active FOXO3 protein can increase long-lasting ovarian reproductive capacity in mice. Trangenic vs non-transgenic mice onto Foxo3+/- vs Foxo3-/- genotype
Project description:During female reproductive life, the reserve of ovarian follicles is reduced by maturation and atresia until menopause ensues. Foxo3 is required to maintain the ovarian reserve in mice. We asked if overexpression of a constitutively active FOXO3 protein can increase long-lasting ovarian reproductive capacity in mice.
Project description:Ovarian reserve defines the female reproductive lifespan, which in humans spans decades due to the robust maintenance of meiotic arrest in non-growing oocytes residing in primordial follicles. Dynamic epigenomic reprogramming and programming occur during mammalian germline and early embryonic development. However, the chromatin-based mechanisms that underlie the establishment and maintenance of ovarian reserves are poorly defined. Here, we report a comprehensive epigenomic landscape of mouse perinatal oocytes and unravel Polycomb-based mechanisms underlying ovarian reserve development. By quantitatively profiling key histone modifications, including the Polycomb-mediated repressive marks H2AK119ub and H3K27me3, and the active marks H3K4me3 and H3K27ac, we identified two major epigenomic transitions: one for ovarian reserve formation from meiotic prophase I to dictyate-arrested non-growing oocytes, and another for ovarian reserve activation from non-growing to growing oocytes. Combining conditional loss-of-function mouse models for Polycomb Repressive Complex 1 or 2 (PRC1/2), we show that PRC1-H2AK119ub and PRC2-H3K27me3 undergo differential dynamics during perinatal oogenesis and have distinct biological functions in ovarian reserve formation and maintenance. Notably, PRC1-H2AK119ub presets the epigenetic states in non-growing oocytes and provides a blueprint for the PRC2-H3K27me3 profile, which is globally reprogrammed as oocytes exit the ovarian reserve and grow. We also demonstrated how coordinated changes of key histone modifications at promoters drive the two major transcriptome transitions during ovarian reserve formation and activation. Importantly, Polycomb complexes play crucial roles in shaping both promoter bivalency and enhancer landscape in the ovarian reserve. Our study determines a comprehensive epigenomic roadmap of perinatal oogenesis, shedding light on how the ovarian reserve is formed, maintained, and activated, emphasizing a critical window of epigenetic programming during female germline development.
Project description:Although it is well established that the ovarian reserve diminishes with increasing age, and that a woman’s age is correlated to lower oocyte quality, the interplay of a diminished reserve and age on oocyte developmental competence is not clear. After maturation, oocytes are mostly transcriptionally quiescent, and developmental competence prior to embryonic genome activation (EGA) relies on maternal RNA and proteins. Age and ovarian reserve both affects oocyte developmental competence, however, their relative importance in this process are difficult to tease out, as ageing is accompanied by a decrease in ovarian reserve. Oocytes store large quantities of RNA, including several noncoding transcripts (ncRNAs) involved in early development transcription and translation modulation. Despite the central role of ncRNAs in maternal to zygote transition, no characterization of the ncRNA transcriptome in human oocytes has been reported. This study aims at identifying how the human oocyte transcriptome changes across reproductive ages and ovarian reserve levels, with the goal of identifying candidate markers of developmental competence, and to assess the independent relevance of age and ovarian reserve in the changes of the transcriptome
Project description:The ovarian reserve defines the female reproductive lifespan, which in humans spans decades due to robust maintenance of meiotic arrest in oocytes residing in primordial follicles. Epigenetic reprogramming, including DNA demethylation, accompanies meiotic entry, but the chromatin changes that underpin the generation and preservation of ovarian reserves are poorly defined. We report that the Polycomb Repressive Complex 1 (PRC1) establishes repressive chromatin states in perinatal mouse oocytes that directly suppress the gene expression program of meiotic prophase-I and thereby enable the transition to dictyate arrest. PRC1 dysfuction causes depletion of the ovarian reserve and leads to premature ovarian failure. Our study demonstrates a fundamental role for PRC1-mediated gene silencing in female reproductive lifespan, and reveals a critical window of epigenetic programming required to establish ovarian reserve.
Project description:We have generated transgenic mice with tetracycline-regulated conditional expression of a constitutively active allele of FoxO3 under the control of the forebrain-specific CaMKIIa promoter. In adult animals, there was a reduction of brain weight by 30% and an almost complete loss of the dorsal dentate gyrus with normal cortical layering. Interestingly, the adult mice showed motor hyperactivity and a selective loss of long-term memory with normal spatial learning. We observed enhanced apoptosis starting from day E10.5. Performing microarray expression analyses and Q-PCR validation with E12.5 forebrain RNA, we observed an over-representation of thalamic markers and an under-representation of cortical markers in transgenic as compared to control animals. Immunohistochemical data show a loss of progenitors in the lateral ventricles. Up-regulation of Pik3ip1 as a target gene of FoxO3 could be responsible for the observed increase in apoptosis. The obtained forebrain expression signature is reminiscent of a Pax6 knockdown phenotype showing that expression of this FoxO3 allele during development affected neural progenitor survival and overall brain development. Conclusion: Neural progenitors are vulnerable to constitutively active FoxO3-induced apoptosis. We sought to determine the transcriptional differences in forebrains from E12.5 mice expressing a constitutively active alleleof FoxO3 under the control of the forebrain-specific CaMKIIa promoter. To this end two time-pregnant dams were sacrificed 12 days after the vaginal plug was detected, and the embryos were prepared. Visual staging of the embryos confirmed their age. Genotyping and luciferase measurements were performed in order to assess presence and acitivity of the transgenes.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:We collected whole genome testis expression data from hybrid zone mice. We integrated GWAS mapping of testis expression traits and low testis weight to gain insight into the genetic basis of hybrid male sterility.