Project description:Transfer of somatic cell nuclei to enucleated eggs or ectopic expression of specific transcription factors are two different reprogramming strategies used to generate pluripotent cells from differentiated cells. However, they are poorly efficient and other unknown factors might be required to increase their success rate. Here, we show that Xenopus egg extracts at the metaphase stage (M phase) have a strong reprogramming activity on mouse embryonic fibroblasts (MEFs). First, they reset replication properties of MEF nuclei toward a replication profile characteristic of early development and they erase several epigenetic marks, such as trimethylation of H3K9, H3K4 and H4K20. Second, when MEFs are reversibly permeabilized in the presence of M phase Xenopus egg extracts, they show a transient increase in cell proliferation, form colonies and start to express specific pluripotency markers. Finally, transient exposure of MEF nuclei to M phase Xenopus egg extracts increases the success of nuclear transfer to enucleated mouse oocytes and strongly synergize with the production of pluripotent stem cells by ectopic expression of transcription factors. The mitotic stage of the egg extract is crucial as neither of these effects is detected when using interphasic Xenopus egg extracts. Our data demonstrate that mitosis is essential to make mammalian somatic nuclei prone to reprogramming and that, surprisingly, the heterologous Xenopus system has features that are conserved enough to remodel mammalian nuclei. MEF cells were infected by retroviruses encoding for Oct4, Sox2, Klf4 and c-Myc and, then reversibly permeabilized and treated with Xenopus M-phase extract. All samples of each cell type (e.g. untreated MEF, ES cells and M-iPS cells) were made in triplicates. Total RNAs were extracted with RNeasy kit and hybridized on Nimblegen MM9 microarrays.
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:Bone marrow stromal cells (BMSCs) are multipotent stem cells that preferentially differentiate into mesenchymal cells. If they can be dedifferentiated into embryonic stem cell-like cells, they will be a highly attractive source for cell therapy. Cell and egg extracts have been used in a few studies to evaluate nuclear reprogramming, but these have not examined cell pluripotency in any detail. In this study, we used a cell reversible permeabilization method to treat BMSC with Xenopus laevis mitotic egg extract. We observed an upregulation of the pluripotent protein Oct3/4 in BMSCs treated by this extract. We also further evaluated transcriptional changes with a focused stem cell oligonucleotide array. A number of genes involved in the Notch or Wnt signaling pathways were upregulated in BMSC exposed to Xenopus egg extract. In conclusion, our microarray data from BMSCs exposure to egg extracts may provide interesting clues regarding factors involved in nuclear reprogramming. Our approach is an alternative method towards dedifferentiation of cells without genetic modification, which is preferable in the clinical situation. Keywords: Cell type comparison Expression profiling was performed on murine bonemarrow stromal cells cultured in-vitro versus stromal cells exposed to Xenopus extract and compared with murine embryonic stem cells
Project description:Comparison of the transcription of palmitoylcarnitine induced pluripotent stem cells, normal induced pluripotent stem cells and embryonic stem cells through RNA-seq
Project description:Transfer of somatic cell nuclei to enucleated eggs or ectopic expression of specific transcription factors are two different reprogramming strategies used to generate pluripotent cells from differentiated cells. However, they are poorly efficient and other unknown factors might be required to increase their success rate. Here, we show that Xenopus egg extracts at the metaphase stage (M phase) have a strong reprogramming activity on mouse embryonic fibroblasts (MEFs). First, they reset replication properties of MEF nuclei toward a replication profile characteristic of early development and they erase several epigenetic marks, such as trimethylation of H3K9, H3K4 and H4K20. Second, when MEFs are reversibly permeabilized in the presence of M phase Xenopus egg extracts, they show a transient increase in cell proliferation, form colonies and start to express specific pluripotency markers. Finally, transient exposure of MEF nuclei to M phase Xenopus egg extracts increases the success of nuclear transfer to enucleated mouse oocytes and strongly synergize with the production of pluripotent stem cells by ectopic expression of transcription factors. The mitotic stage of the egg extract is crucial as neither of these effects is detected when using interphasic Xenopus egg extracts. Our data demonstrate that mitosis is essential to make mammalian somatic nuclei prone to reprogramming and that, surprisingly, the heterologous Xenopus system has features that are conserved enough to remodel mammalian nuclei.
Project description:Bone marrow stromal cells (BMSCs) are multipotent stem cells that preferentially differentiate into mesenchymal cells. If they can be dedifferentiated into embryonic stem cell-like cells, they will be a highly attractive source for cell therapy. Cell and egg extracts have been used in a few studies to evaluate nuclear reprogramming, but these have not examined cell pluripotency in any detail. In this study, we used a cell reversible permeabilization method to treat BMSC with Xenopus laevis mitotic egg extract. We observed an upregulation of the pluripotent protein Oct3/4 in BMSCs treated by this extract. We also further evaluated transcriptional changes with a focused stem cell oligonucleotide array. A number of genes involved in the Notch or Wnt signaling pathways were upregulated in BMSC exposed to Xenopus egg extract. In conclusion, our microarray data from BMSCs exposure to egg extracts may provide interesting clues regarding factors involved in nuclear reprogramming. Our approach is an alternative method towards dedifferentiation of cells without genetic modification, which is preferable in the clinical situation. Keywords: Cell type comparison
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.