Project description:The in vitro derivation and propagation of spermatogonial stem cells (SSCs) from pluripotent stem cells (PSCs) is a key goal in reproductive science. We show here that when aggregated with embryonic testicular somatic cells (reconstituted testes), primordial germ cell-like cells (PGCLCs) induced from mouse embryonic stem cells differentiate into spermatogonia-like cells in vitro and are expandable as cells that resemble germline stem cells (GSCs), a primary cell line with SSC activity. Remarkably, GSC-like cells (GSCLCs), but not PGCLCs, colonize adult testes and, albeit less effectively than GSCs, contribute to spermatogenesis and fertile offspring. Whole-genome analyses reveal that GSCLCs exhibit aberrant methylation at vulnerable regulatory elements, including those critical for spermatogenesis, which may restrain their spermatogenic potential. Our study establishes a strategy for the in vitro derivation of SSC activity from PSCs, which, we propose, relies on faithful epigenomic regulation.
Project description:The in vitro derivation and propagation of spermatogonial stem cells (SSCs) from pluripotent stem cells (PSCs) is a key goal in reproductive science. We show here that when aggregated with embryonic testicular somatic cells (reconstituted testes), primordial germ cell-like cells (PGCLCs) induced from mouse embryonic stem cells differentiate into spermatogonia-like cells in vitro and are expandable as cells that resemble germline stem cells (GSCs), a primary cell line with SSC activity. Remarkably, GSC-like cells (GSCLCs), but not PGCLCs, colonize adult testes and, albeit less effectively than GSCs, contribute to spermatogenesis and fertile offspring. Whole-genome analyses reveal that GSCLCs exhibit aberrant methylation at vulnerable regulatory elements, including those critical for spermatogenesis, which may restrain their spermatogenic potential. Our study establishes a strategy for the in vitro derivation of SSC activity from PSCs, which, we propose, relies on faithful epigenomic regulation.
Project description:We developed and report on a novel new technique to reprogramm fobroblasts from two non-permissive mouse backgrounds into emrbyonic stem cell-like induced pluripotent stem cells
Project description:We have developed a method for derivation of mfNPCs from human induced pluripotent stem cells (hIPSC), that are only dependent on small molecules stimulating WNT and SHH signalling for their propagation.
Project description:In vitro and in vivo aging of mouse spermatogonial stem cells alters stem cell function based on quantitative spermatogonial stem cell transplantation analyses. We used microarrays to identify differential gene expression in vitro and in vivo aged spermatogonial stem cells to identify potential causes of observed phenotypic differences in aged spermatogonial stem cell function. Spermatogonial stem cells were isolated from young and serial-transplanted aged mouse donors and cultured for short and long periods. Spermatogonial stem cells were isolated from cultures and subjected to microarray analysis to identify differential gene expression.
Project description:Spermatogonial stem cells (SSCs) have pluripotent potential. However, frequency of pluripotent cell derivation is low and the mechanism of culture-induced reprogramming remains unknown. Here we report that epigenetic instability of germline stem (GS) cells, cultured SSCs, induces pluripotent cell derivation. GS cells undergo DNA demethylation in H19 differentially methylated region under low-density culture. When H19 demethylation was induced by Dnmt1 depletion, they converted into embryonic stem (ES)-like cells. Dnmt1 depletion downregulated Dmrt1 expression, whose depletion also induced pluripotency. Functional screening of Dmrt1 target gene revealed that Dmrt1 depletion upregulates Sox2, the key molecule responsible for generating induced pluripotent stem cells. Although Sox2 transfection upregulated Oct4 and produced pluripotent cells, this conversion was inhibited by Oct1 overexpression, suggesting that the balance of Oct proteins maintains SSC identity. These results suggest that culture-induced reprogramming is caused by unstable DNA methylation, and that Dmrt1-Sox2 cascade is critical for regulating pluripotency in SSCs. Pluripotent stem-like cells were induced from GS cells by down-regulation of Dnmt/Dmrt, or up-regulation of Sox2/Oct4 in combination with p53 knock-down and their total RNA samples were subjected to microarray analysis to compare their gene expression profile with other pluripotent stem cells such as ES cells or iPS 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:A transcriptome study in mouse hematopoietic stem cells was performed using a sensitive SAGE method, in an attempt to detect medium and low abundant transcripts expressed in these cells. Among a total of 31,380 unique transcript, 17,326 (55%) known genes were detected, 14,054 (45%) low-copy transcripts that have no matches to currently known genes. 3,899 (23%) were alternatively spliced transcripts of the known genes and 3,754 (22%) represent anti-sense transcripts from known genes.