Project description:TG-interacting factor1 (Tgif1) maintains the identity of mouse ES cells by counterbalancing the expression of core pluripotency factors.
Project description:The pluripotency of embryonic stem cells (ESCs) is maintained by a small group of master transcription factors including Oct4, Sox2 and Nanog. These core factors form a regulatory circuit controlling the transcription of a number of pluripotency factors including themselves. Although a lot of previous studies have identified key factors regulating this core network in trans, the contribution of cis-regulatory DNA sequences on the transcription of these key pluripotency factors remains elusive. We analyzed epigenomic data within the 1.5 Mb gene-desert regions around Sox2 gene and predicted only one 13kb-long enhancer located 100kb downstream of Sox2 in mouse ES cells. This enhancer is occupied by Oct4, Sox2, Nanog, and mediator complex and forms a long-range DNA looping to Sox2 locus. We hypothesized that this enhancer is critical for Sox2 gene expression and tested this hypothesis by deleting this entire 13-kb enhancer with a simple highly-efficient double-excision CRISPR strategy. Allele-specific of Sox2 transcripts in heterozygous enhancer-deletion clones showed that the enhancer affects expression through a cis-acting mechanism. Strikingly, although this distal enhancer is not conserved in other mammals including human, it is responsible for over 90% of Sox2 expression in mouse ESCs. Taken together, our results provide direct evidence that in mouse ESCs, Sox2 transcription is primarily driven by a species-specific distal enhancer, which may provide new perspectives explaining the physiological difference between human and mouse ES cells. This dataset include ChIP-seq of H3K4me3 and H3K27ac in a hybrid mouse ES cells (F123). H3K27ac in J1 mouse ES cells. And RNA-seq in F123 mESCs with complete Sox2 enhancer deletion or enhancer haploinsufficient clones.
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.