Project description:Specification to primordial germ cells (PGCs) occurs under the mesoderm induction signals during gastrulation. Here, we found that Akt activation in embryonic stem (ES) cells generated self-renewing spheres during mesodermal differentiation induction and that the differentiation status of the sphere cells was in between ES cells and PGCs. Essential regulators for PGC specification and their downstream germ cell-specific genes were expressed in the spheres, showing that the cells of the sphere commenced the differentiation to germ lineage. However, the spheres could not proceed to spermatogenesis after transplantation to testes. Meanwhile, the transfer of the spheres to the original feeder-free ES cell culture conditions induced chaotic differentiation. In contrast, when the spheres were cultured on mouse embryonic fibroblasts or in the presence of ERK-cascade and GSK3 inhibitors, the reversion to the ES cell-like cell states was induced. These results indicate that the Akt signaling brings about a novel metastable and pluripotent state between ES cells and PGCs. Five samples were analyzed, which included the Akt-Mer-expressing ES cell (ESC) line #21 treated with or without 4OHT (4-hydroxytamoxifen), the #21 ESC-derived primordial germ cell (PGC)-like sphere cells and the ESC-like cells reverted from #21 PGC-like sphere cells. The PGC-like sphere cells derived from another Akt-Mer ESC line #42 was also examined.
Project description:Specification to primordial germ cells (PGCs) occurs under the mesoderm induction signals during gastrulation. Here, we found that Akt activation in embryonic stem (ES) cells generated self-renewing spheres during mesodermal differentiation induction and that the differentiation status of the sphere cells was in between ES cells and PGCs. Essential regulators for PGC specification and their downstream germ cell-specific genes were expressed in the spheres, showing that the cells of the sphere commenced the differentiation to germ lineage. However, the spheres could not proceed to spermatogenesis after transplantation to testes. Meanwhile, the transfer of the spheres to the original feeder-free ES cell culture conditions induced chaotic differentiation. In contrast, when the spheres were cultured on mouse embryonic fibroblasts or in the presence of ERK-cascade and GSK3 inhibitors, the reversion to the ES cell-like cell states was induced. These results indicate that the Akt signaling brings about a novel metastable and pluripotent state between ES cells and PGCs.
Project description:Embryonic stem (ES) cells can self-renew indefinitely without losing their differentiation ability to any cell types. Phosphoinositide-3 kinase (PI3K)/Akt signaling plays a pivotal role in various stem cell systems, including the formation of embryonic germ (EG) cells from primordial germ cells and self-renewal of neural stem cells. Here, we show that myristoylated, active form of Akt (myr-Akt) maintained the undifferentiated phenotypes in mouse ES cells without the addition of leukemia inhibitory factor (LIF). The effects of myr-Akt were reversible, because LIF dependence and pluripotent differentiation activity were restored by the deletion of myr-Akt. In addition, myr-Akt-Mer fusion protein, whose enzymatic activity is controlled by 4-hydroxy-tamoxifen, also maintained the pluripotency of not only mouse but also cynomolgus monkey ES cells. These results clearly demonstrate that Akt signaling sufficiently maintains pluripotency in mouse and primate ES cells, and support the notion that PI3K/Akt signaling axis regulates 'stemness' in a broad spectrum of stem cell systems.
Project description:The molecular mechanisms of human primordial germ cell (PGC) specification are poorly understood due to the inaccessibility of cell materials and the lack of an alternative in vitro model that enables tracking of the earliest stages of germ cell development. Here, we introduce a defined and efficient differentiation system for the induction of pre-migratory PGC-like cells from human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). By step-wise differentiation, we generated an OCT4+/ T+/BLIMP1+ cell population that transitioned into STELLA expressing PGC-like cells that exhibited a similar key gene expression as mouse PGCs as well as global epigenetic reprogramming. Even though, these PGC-like cells expressed PRDM14 at very low levels, they underwent activation of pluripotency/PGC genes, suppression of neural induction and suppression of de novo DNA methylation, events that are regulated by Prdm14 during mouse PGC specification. This study demonstrates that human PGC commitment shares many key features with mouse PGC specification, but harbors unique and so far unknown mechanisms that, point to a novel human transcriptional regulation. 7 samples were analyzed. ESC: Human Embryonic Stem Cells, 1 biological rep iPSC: Human induced Pluripotent Stem Cells, 1 biological rep d2: Human induced Pluripotent Stem Cells, 2 days differentiation treatment , 2 biological rep d4PGCLC: Human induced Pluripotent Stem Cells, 4 days differentiation treatment towards Primordial Germ Cells Like Cells, 1 biological rep d6PGCLC: Human induced Pluripotent Stem Cells, 6 days differentiation treatment towards Primordial Germ Cells Like Cells, 2 biological rep
Project description:Embryonic stem (ES) cells can self-renew indefinitely without losing their differentiation ability to any cell types. Phosphoinositide-3 kinase (PI3K)/Akt signaling plays a pivotal role in various stem cell systems, including the formation of embryonic germ (EG) cells from primordial germ cells and self-renewal of neural stem cells. Here, we show that myristoylated, active form of Akt (myr-Akt) maintained the undifferentiated phenotypes in mouse ES cells without the addition of leukemia inhibitory factor (LIF). The effects of myr-Akt were reversible, because LIF dependence and pluripotent differentiation activity were restored by the deletion of myr-Akt. In addition, myr-Akt-Mer fusion protein, whose enzymatic activity is controlled by 4-hydroxy-tamoxifen, also maintained the pluripotency of not only mouse but also cynomolgus monkey ES cells. These results clearly demonstrate that Akt signaling sufficiently maintains pluripotency in mouse and primate ES cells, and support the notion that PI3K/Akt signaling axis regulates 'stemness' in a broad spectrum of stem cell systems. Keywords: other
Project description:Transcriptomes of mouse E12.5 primordial germ cells (PGCs), primordial germ cell-like cells (PGCLCs) isolated from 6-day culture embryoid bodies, and the precursor pluripotent stem cells [embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs)] and epiblast-like cells (EpiLCs) Total RNA was isolated from FACS-enriched, SSEA1+/CD61+ double-positive PGCs and PGCLCs. RNA was also isolated from ESC, iPSC, and EpiLC cultured without enrichment. Transcriptomes were determined using Affymetrix microarray.