Project description:Estrogen (E2) signaling through its nuclear receptor, estrogen receptor α (ERα) increases insulin-like growth factor 1 (IGF1) in the rodent uterus, which then initiates further signals via the IGF1 receptor (IGF1R). Directly administering IGF1 results in similar biological and transcriptional uterine responses. Our studies using global ERα-null mice demonstrated a loss of uterine biological responses of the uterus to E2 or IGF1 treatment, while maintaining transcriptional responses to IGF1. To address this discrepancy in the need for uterine ERα in mediating the IGF1 transcriptional vs. growth responses, we assessed the IGF1 transcriptional responses in PgrCre+Esr1f/f (called ERαUtcKO) mice, which selectively lack ERα in progesterone receptor (PGR) expressing cells, including all uterine cells, while maintaining ERα expression in other tissues and cells that do not express Pgr. Additionally, we profiled IGF1-induced ERα binding sites in uterine chromatin using ChIP-seq. Herein, we explore the transcriptional and molecular signaling that underlies our findings to refine our understanding of uterine IGF1 signaling and identify ERα-mediated and ERα-independent uterine transcriptional responses. Defining these mechanisms in vivo in whole tissue and animal contexts provides details of nuclear receptor mediated mechanisms that impact biological systems and have potential applicability to reproductive processes of humans, livestock and wildlife.
Project description:Estrogen (E2) signaling through its nuclear receptor, estrogen receptor α (ERα) increases insulin-like growth factor 1 (IGF1) in the rodent uterus, which then initiates further signals via the IGF1 receptor (IGF1R). Directly administering IGF1 results in similar biological and transcriptional uterine responses. Our studies using global ERα-null mice demonstrated a loss of uterine biological responses of the uterus to E2 or IGF1 treatment, while maintaining transcriptional responses to IGF1. To address this discrepancy in the need for uterine ERα in mediating the IGF1 transcriptional vs. growth responses, we assessed the IGF1 transcriptional responses in PgrCre+Esr1f/f (called ERαUtcKO) mice, which selectively lack ERα in progesterone receptor (PGR) expressing cells, including all uterine cells, while maintaining ERα expression in other tissues and cells that do not express Pgr. Additionally, we profiled IGF1-induced ERα binding sites in uterine chromatin using ChIP-seq. Herein, we explore the transcriptional and molecular signaling that underlies our findings to refine our understanding of uterine IGF1 signaling and identify ERα-mediated and ERα-independent uterine transcriptional responses. Defining these mechanisms in vivo in whole tissue and animal contexts provides details of nuclear receptor mediated mechanisms that impact biological systems and have potential applicability to reproductive processes of humans, livestock and wildlife.
Project description:ERa DNA Binding Profiles of IGF1 and ICI182,780 treated mouse uterus from manuscript: Role of ERα in Mediating Female Uterine Transcriptional Responses to IGF1
Project description:Insulin-like growth factor 1 (IGF1) is primarily synthesized in and secreted from the liver; however, estrogen (E2), through E2 receptor α (ERα), increases uterine Igf1 mRNA levels. Previous ChIP-Seq analyses of the murine uterus have revealed a potential enhancer region distal from the Igf1 transcription start site (TSS) with multiple E2-dependent ERα-binding regions. Here, we show E2-dependent super enhancer–associated characteristics and suggest contact between the distal enhancer and the Igf1 TSS. We hypothesized that this distal super-enhancer region controls E2-responsive induction of uterine Igf1 transcripts. We deleted 430 bp, encompassing one of the ERα-binding sites, thereby disrupting interactions of the enhancer with gene-regulatory factors. As a result, E2-mediated induction of mouse uterine Igf1 mRNA is completely eliminated, whereas hepatic Igf1 expression remains unaffected. This highlights the central role of a distal enhancer in the assembly of the factors necessary for E2-dependent interaction with the Igf1 TSS and induction of uterus-specific Igf1 transcription. Of note, loss of the enhancer did not affect fertility or uterine growth responses. Deletion of uterine Igf1 in a PgrCre;Igf1f/f model decreased female fertility, but did not impact the E2-induced uterine growth response. Moreover, E2-dependent activation of uterine IGF1 signaling was not impaired by disrupting the distal enhancer or by deleting the coding transcript. This indicated a role for systemic IGF1, suggested that other growth mediators drive uterine response to E2, and that uterine-derived IGF1 is essential for reproductive success. Our findings elucidate the role of a super enhancer in Igf1 regulation and uterine growth.
Project description:Estrogens stimulate hypertrophy and hyperplasia in the uterus and exert their activity through estrogen receptor α (ERα). A uterine epithelial ERα conditional knockout mouse model (Wnt7aCre+;Esr1f/f or cKO) demonstrated that ERα in the epithelial cells was dispensable for an early uterine proliferative response to 17β-estradiol (E2), but required for subsequent uterine biological responses. We compared the gene expression profile in the uterus after E2 treatment in the cKO samples with WT samples. We found that approximately 25% of the genes differentially expressed at 2 h were epithelial ERα independent, as they were preserved in the cKO, indicating they are mediated from the stroma and sufficient to promote initial proliferative responses. However, more than 90% of the differentially expressed transcripts at 24 h were absent in the cKO, indicating the majority of later transcriptional regulation required epithelial ERα and suggesting the loss of regulation of these later transcripts results in the blunted growth response 3 days after treatment. These transcription profiles correlate with our previous biological responses, in which the initial proliferative response is independent of epithelial ERα but dependent on stromal ERα, yet epithelial ERα is essential for subsequent tissue responsiveness. These analyses are now allowing for in vivo determination of the cell specific actions of ERα in the female reproductive tract.
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:Translational research is commonly performed in the C57B6/J mouse strain, chosen for its genetic homogeneity and phenotypic uniformity. Here, we evaluate the suitability of the white-footed deer mouse (Peromyscus leucopus) as a model organism for aging research, offering a comparative analysis against C57B6/J and diversity outbred (DO) Mus musculus strains. Our study includes comparisons of body composition, skeletal muscle function, and cardiovascular parameters, shedding light on potential applications and limitations of P. leucopus in aging studies. Notably, P. leucopus exhibits distinct body composition characteristics, emphasizing reduced muscle force exertion and a unique metabolism, particularly in fat mass. Cardiovascular assessments showed changes in arterial stiffness, challenging conventional assumptions and highlighting the need for a nuanced interpretation of aging-related phenotypes. Our study also highlights inherent challenges associated with maintaining and phenotyping P. leucopus cohorts. Behavioral considerations, including anxiety-induced responses during handling and phenotyping assessment, pose obstacles in acquiring meaningful data. Moreover, the unique anatomy of P. leucopus necessitates careful adaptation of protocols designed for Mus musculus. While showcasing potential benefits, further extensive analyses across broader age ranges and larger cohorts are necessary to establish the reliability of P. leucopus as a robust and translatable model for aging studies.
Project description:At birth, all female mice, including those that either lack estrogen receptor α (ERα-knockout) or that express mutated forms of ERα (AF2ERKI), have a hypoplastic uterus. However, uterine growth and development that normally accompanies pubertal maturation does not occur in ERα-knockout or AF2ERKI mice, indicating ERα mediated estrogen signaling is essential for this process. Mice that lack Cyp19 (aromatase, ArKO mice), an enzyme critical for estrogen (E2) synthesis, are unable to make E2, and lack pubertal uterine development. A single injection of E2 into ovariectomized adult (10 weeks old) females normally results in uterine epithelial cell proliferation, however, we observe that, although ERα is present in the ArKO uterine cells, no proliferative response is seen. We assessed the impact of exposing ArKO mice to E2 during pubertal and post-pubertal windows and observed that E2 exposed ArKO mice acquired growth responsiveness. Analysis of differential gene expression between unexposed ArKO samples and samples from animals exhibiting the ability to mount an E2-induced uterine growth response (WT or E2 exposed ArKO) revealed activation of EZH2 and HAND2 signaling and inhibition of GLI1 responses. EZH2 and HAND2 are known inhibit uterine growth, and GLI1 is involved in IHH signaling, which is a positive mediator of uterine response. Finally, we show that exposure of ArKO females to dietary phytoestrogens results in their acquisition of uterine growth competence. Altogether our findings suggest that pubertal levels of endogenous and exogenous estrogens impact biological function of uterine cells later in life via ERα-dependent mechanisms. We compared uterine RNA from ovariectomized adult aromatase knockout mice (ARKO) mice that were untreated to WT mice and to ARKO that were administered estradiol benzoate (EB) to induce uterine epithelial cell growth competence
Project description:BackgroundCopy number variation is an important dimension of genetic diversity and has implications in development and disease. As an important model organism, the mouse is a prime candidate for copy number variant (CNV) characterization, but this has yet to be completed for a large sample size. Here we report CNV analysis of publicly available, high-density microarray data files for 351 mouse tail samples, including 290 mice that had not been characterized for CNVs previously.ResultsWe found 9634 putative autosomal CNVs across the samples affecting 6.87% of the mouse reference genome. We find significant differences in the degree of CNV uniqueness (single sample occurrence) and the nature of CNV-gene overlap between wild-caught mice and classical laboratory strains. CNV-gene overlap was associated with lipid metabolism, pheromone response and olfaction compared to immunity, carbohydrate metabolism and amino-acid metabolism for wild-caught mice and classical laboratory strains, respectively. Using two subspecies of wild-caught Mus musculus, we identified putative CNVs unique to those subspecies and show this diversity is better captured by wild-derived laboratory strains than by the classical laboratory strains. A total of 9 genic copy number variable regions (CNVRs) were selected for experimental confirmation by droplet digital PCR (ddPCR).ConclusionThe analysis we present is a comprehensive, genome-wide analysis of CNVs in Mus musculus, which increases the number of known variants in the species and will accelerate the identification of novel variants in future studies.
Project description:BackgroundLong terminal repeat (LTR) retrotransposons make up a large fraction of the typical mammalian genome. They comprise about 8% of the human genome and approximately 10% of the mouse genome. On account of their abundance, LTR retrotransposons are believed to hold major significance for genome structure and function. Recent advances in genome sequencing of a variety of model organisms has provided an unprecedented opportunity to evaluate better the diversity of LTR retrotransposons resident in eukaryotic genomes.ResultsUsing a new data-mining program, LTR_STRUC, in conjunction with conventional techniques, we have mined the GenBank mouse (Mus musculus) database and the more complete Ensembl mouse dataset for LTR retrotransposons. We report here that the M. musculus genome contains at least 21 separate families of LTR retrotransposons; 13 of these families are described here for the first time.ConclusionsAll families of mouse LTR retrotransposons are members of the gypsy-like superfamily of retroviral-like elements. Several different families of unrelated non-autonomous elements were identified, suggesting that the evolution of non-autonomy may be a common event. High sequence similarity between several LTR retrotransposons identified in this study and those found in distantly-related species suggests that horizontal transfer has been a significant factor in the evolution of mouse LTR retrotransposons.