Project description:Female human induced pluripotent stem cell (hiPSC) lines exhibit considerable variability in X-inactivation status. Some lines maintain one transcriptionally active X chromosome (Xa) and one inactive X (Xi) from donor cells. However, hiPSC lines that have two Xas are infrequently produced. We show here Xinactivation status in female hiPSC lines depends on derivation conditions. hiPSC lines generated using the Kyoto method, which employs leukemia inhibitory factor (LIF)-expressing SNL feeders, frequently had two Xas. Lines derived on other feeders maintained an Xi. In addition, there appears to be a window in which SNL feeders promote Xi-reactivation. Upon differentiation, Xa/Xa hiPSCs silenced one X. The efficient production of Xa/Xa hiPSC lines provides unprecedented opportunities to understand human X-reactivation and inactivation. Gene expression patterns were compared between several human embryonic stem cell (hESC) and hiPSC lines. Gene expression ratios between genes on X and those on autosomes were calculated from each cell lines.
Project description:Female human induced pluripotent stem cell (hiPSC) lines exhibit considerable variability in X-inactivation status. Some lines maintain one transcriptionally active X chromosome (Xa) and one inactive X (Xi) from donor cells. However, hiPSC lines that have two Xas are infrequently produced. We show here Xinactivation status in female hiPSC lines depends on derivation conditions. hiPSC lines generated using the Kyoto method, which employs leukemia inhibitory factor (LIF)-expressing SNL feeders, frequently had two Xas. Lines derived on other feeders maintained an Xi. In addition, there appears to be a window in which SNL feeders promote Xi-reactivation. Upon differentiation, Xa/Xa hiPSCs silenced one X. The efficient production of Xa/Xa hiPSC lines provides unprecedented opportunities to understand human X-reactivation and inactivation. Gene expression patterns were compared between several human embryonic stem cell (hESC) and hiPSC lines. Gene expression ratios between genes on X and those on autosomes were calculated from each cell lines.
Project description:Female human induced pluripotent stem cell (hiPSC) lines exhibit considerable variability in X-inactivation status. Some lines maintain one transcriptionally active X chromosome (Xa) and one inactive X (Xi) from donor cells. However, hiPSC lines that have two Xas are infrequently produced. We show here Xinactivation status in female hiPSC lines depends on derivation conditions. hiPSC lines generated using the Kyoto method, which employs leukemia inhibitory factor (LIF)-expressing SNL feeders, frequently had two Xas. Lines derived on other feeders maintained an Xi. In addition, there appears to be a window in which SNL feeders promote Xi-reactivation. Upon differentiation, Xa/Xa hiPSCs silenced one X. The efficient production of Xa/Xa hiPSC lines provides unprecedented opportunities to understand human X-reactivation and inactivation.
Project description:Female human induced pluripotent stem cell (hiPSC) lines exhibit considerable variability in X-inactivation status. Some lines maintain one transcriptionally active X chromosome (Xa) and one inactive X (Xi) from donor cells. However, hiPSC lines that have two Xas are infrequently produced. We show here Xinactivation status in female hiPSC lines depends on derivation conditions. hiPSC lines generated using the Kyoto method, which employs leukemia inhibitory factor (LIF)-expressing SNL feeders, frequently had two Xas. Lines derived on other feeders maintained an Xi. In addition, there appears to be a window in which SNL feeders promote Xi-reactivation. Upon differentiation, Xa/Xa hiPSCs silenced one X. The efficient production of Xa/Xa hiPSC lines provides unprecedented opportunities to understand human X-reactivation and inactivation.
Project description:Erasure of epigenetic memory is required to convert somatic cells towards pluripotency. Reactivation of the inactive X chromosome (Xi) has been used to model epigenetic reprogramming in mouse, but human studies are hampered by Xi epigenetic instability and difficulties in tracking partially reprogrammed iPSCs. Here we used cell fusion to examine the earliest events in the reprogramming-induced Xi reactivation of human female fibroblasts. We show a rapid and widespread loss of Xi-associated H3K27me3 and XIST in fused cells that precedes the bi-allelic expression of selected Xi-genes by many heterokaryons (30-50%). After cell division, RNA-FISH and RNA-Seq analysis confirmed that Xi reactivation remained partial and showed that induction of human pluripotency-specific XACT transcripts occurred, but was rare (1%). These data effectively separate pre- and post-mitotic events in reprogramming-induced Xi reactivation, and suggest a hierarchy where early events such as XIST-delocalisation, are required but are insufficient to establish stable human X reactivation. We performed RNA-sequencing of human fibroblast clones derived from TERT-immortalised NHDF17914 (Lonza) before and at 5 days after fusion with mouse ESC (E14Tg2a:puroR). Two biological replicates were performed and sequenced.
Project description:Erasure of epigenetic memory is required to convert somatic cells towards pluripotency. Reactivation of the inactive X chromosome (Xi) has been used to model epigenetic reprogramming in mouse, but human studies are hampered by Xi epigenetic instability and difficulties in tracking partially reprogrammed iPSCs. Here we used cell fusion to examine the earliest events in the reprogramming-induced Xi reactivation of human female fibroblasts. We show a rapid and widespread loss of Xi-associated H3K27me3 and XIST in fused cells that precedes the bi-allelic expression of selected Xi-genes by many heterokaryons (30-50%). After cell division, RNA-FISH and RNA-Seq analysis confirmed that Xi reactivation remained partial and showed that induction of human pluripotency-specific XACT transcripts occurred, but was rare (1%). These data effectively separate pre- and post-mitotic events in reprogramming-induced Xi reactivation, and suggest a hierarchy where early events such as XIST-delocalisation, are required but are insufficient to establish stable human X reactivation.
Project description:Human in vitro oogenesis provides a framework for clarifying the mechanism of human oogenesis. To create its benchmark, it is vital to promote in vitro oogenesis using a model physiologically close to humans. Here, we establish a foundation for in vitro oogenesis in cynomolgus (cy) monkeys (Macaca fascicularis): cy female embryonic stem cells harboring one active and one inactive X chromosome (Xa and Xi, respectively) differentiate robustly into primordial germ cell-like cells, which in xenogeneic reconstituted ovaries develop efficiently into oogonia and, remarkably, further into meiotic oocytes at the zygotene stage. This differentiation entails comprehensive epigenetic reprogramming, including Xi reprogramming, yet Xa and Xi remain epigenetically asymmetric with, as partly observed in vivo, incomplete Xi reactivation. In humans and monkeys, the Xi epigenome in pluripotent stem cells functions as an Xi-reprogramming determinant. We further show that developmental pathway over-activations with suboptimal up-regulation of relevant meiotic genes impede in vitro meiotic progression. Cy in vitro oogenesis exhibits critical homology with the human system, including with respect to bottlenecks, providing a salient model for advancing human in vitro oogenesis.
Project description:Human in vitro oogenesis provides a framework for clarifying the mechanism of human oogenesis. To create its benchmark, it is vital to promote in vitro oogenesis using a model physiologically close to humans. Here, we establish a foundation for in vitro oogenesis in cynomolgus (cy) monkeys (Macaca fascicularis): cy female embryonic stem cells harboring one active and one inactive X chromosome (Xa and Xi, respectively) differentiate robustly into primordial germ cell-like cells, which in xenogeneic reconstituted ovaries develop efficiently into oogonia and, remarkably, further into meiotic oocytes at the zygotene stage. This differentiation entails comprehensive epigenetic reprogramming, including Xi reprogramming, yet Xa and Xi remain epigenetically asymmetric with, as partly observed in vivo, incomplete Xi reactivation. In humans and monkeys, the Xi epigenome in pluripotent stem cells functions as an Xi-reprogramming determinant. We further show that developmental pathway over-activations with suboptimal up-regulation of relevant meiotic genes impede in vitro meiotic progression. Cy in vitro oogenesis exhibits critical homology with the human system, including with respect to bottlenecks, providing a salient model for advancing human in vitro oogenesis.