Project description:The role of microRNAs (miRNA) in first cell fate choice of the preimplantation mouse embryo remains unresolved, as gene expression and knockout data are conflicting. This cell fate choice generates the extraembryonic lineage of the trophoblast and the embryonic lineage of the epiblast (inner cell mass). The trophoblast differentiates into polar and mural cells, where polar cells contribute to placental development and mural cells to the implantation process and Reichert’s membrane. The inner cell mass further differentiates into the epiblast and primitive endoderm. We used stem cell lines that can be derived from the trophoblast and epiblast lineages to address the role of miRNAs in early lineage cell fate specification and determination. Using embryonic stem cells (ESC) and trophoblast stem cells (TSC) as starting and ending states of cell development we identified a network of TSC expressed miRNAs that are enriched in ESC targets mRNA. We used constitutive and inducible expression of TSC enriched miRNAs in ESC and show that they can drive cell morphology and gene expression profiles similar to trophoblast. Additionally we show that this process required HDAC2 inhibition and is miRNA specific, as cardiac specific miR-1 could not induce trophoblast under these conditions. In contrast to embryo derived and Cdx2 induced trophoblast cells, miRNAs promote a mural TE like cell phenotype. Transplantation into preimplantation mouse embryos showed that miRNA-induced trophoblast preferentially contributes to the mural trophoblast in both the blastocyst and the Reichert’s membrane. Our data support a role for miRNAs and HDACs in the specification of the trophoblast and potentially the polar and mural cell types.
Project description:The first lineage decisions during mouse development lead to establishment of embryonic and extraembryonic tissues. The transcription factor Cdx2 plays a central role by repressing pluripotency genes, such as Oct4 and promoting trophoblast fate at the blastocyst stage. Here we show that the transcription factor Gata3 is coexpressed with Cdx2 in the blastocyst and that overexpression of Gata3 in embryonic stem cells is sufficient to induce expression of trophoblast genes. Gata3 expression in the blastocyst does not depend on Cdx2, nor do Gata3 overexpressing cell lines require Cdx2 for expression of a subset of trophoblast genes. In the embryo, expression of Gata3, like Cdx2, depends on Tead4, and expression of both factors becomes restricted to nascent trophoblast by an Oct4-independent mechanism. These observations place Tead4 at the top of a trophoblast hierarchy, with Gata3 and Cdx2 acting downstream to induce expression of common and independent targets in this lineage. This SuperSeries is composed of the following subset Series: GSE12985: Differentiation time course of trophoblast stem cells GSE12986: Expression of Cdx2 or Gata3 in R1 mouse embryonic stem cells
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:GATA transcription factors are implicated in establishing cell fate during mammalian development. In early mammalian embryos, GATA3 is selectively expressed in the extraembryonic trophoblast lineage and regulates gene expression to promote trophoblast fate. However, trophoblast-specific GATA3 function is dispensable for early mammalian development. Here, using dual conditional knockout mice, we show that genetic redundancy of GATA3 with paralog GATA2 in trophoblast progenitors ensures the successful progression of both pre and postimplantation mammalian development. Stage-specific gene deletion in trophoblasts reveals that loss of both GATA genes, but not either one alone, leads to embryonic lethality prior to the onset of their expression within the embryo proper. Using ChIP-seq and RNA-seq analyses, we define the global targets of GATA2/GATA3 and show that they directly regulate a large number of common genes to orchestrate stem vs. differentiated trophoblast fate. Also, in trophoblast progenitors GATA factors directly regulate BMP4, Nodal and Wnt signaling components that promote embryonic-extraembryonic signaling cross-talk, essential for the development of the embryo proper. Our study provides genetic evidence that impairment of trophoblast-specific GATA2/GATA3 function could lead to early pregnancy failure.
Project description:GATA transcription factors are implicated in establishing cell fate during mammalian development. In early mammalian embryos, GATA3 is selectively expressed in the extraembryonic trophoblast lineage and regulates gene expression to promote trophoblast fate. However, trophoblast-specific GATA3 function is dispensable for early mammalian development. Here, using dual conditional knockout mice, we show that genetic redundancy of GATA3 with paralog GATA2 in trophoblast progenitors ensures the successful progression of both pre and postimplantation mammalian development. Stage-specific gene deletion in trophoblasts reveals that loss of both GATA genes, but not either one alone, leads to embryonic lethality prior to the onset of their expression within the embryo proper. Using ChIP-seq and RNA-seq analyses, we define the global targets of GATA2/GATA3 and show that they directly regulate a large number of common genes to orchestrate stem vs. differentiated trophoblast fate. Also, in trophoblast progenitors GATA factors directly regulate BMP4, Nodal and Wnt signaling components that promote embryonic-extraembryonic signaling cross-talk, essential for the development of the embryo proper. Our study provides genetic evidence that impairment of trophoblast-specific GATA2/GATA3 function could lead to early pregnancy failure.
Project description:Cellular binary fate decisions require the progeny to silence genes associated with the alternative fate. The major subsets of alpha:beta T cells have been extensively studied as a model system for fate decisions. While the transcription factor RUNX3 is required for the initiation of Cd4 silencing in CD8 T cell progenitors, it is not required to maintain the silencing of Cd4 and other helper T lineage genes. The other runt domain containing protein, RUNX1, silences Cd4 in an earlier T cell progenitor, but this silencing is reversed whereas the gene silencing after RUNX3 expression is not reverse. Therefore, we hypothesized that RUNX3 and not RUNX1 recruits other factors that maintains the silencing of helper T lineage genes in CD8 T cells. To this end, we performed a proteomics screen of RUNX1 and RUNX3 to determine candidate silencing factors.