Project description:Embryonic stem cell (ESC) cultures display a heterogeneous gene expression profile, ranging from a pristine naïve pluripotent state to a primed epiblast state. While it is known that the addition of inhibitors of GSK3β and MEK (so-called 2i conditions) push ESC cultures towards a more homogeneous naïve pluripotent state, the molecular underpinnings of this naïve transition are not completely understood. Here we demonstrate that Dazl, a RNA-binding protein previously thought to be expressed specifically in developing primordial germ cells (PGCs), marks a subpopulation of ESCs in vitro that is actively transitioning toward naïve pluripotency. In the absence of Dazl expression, ESCs fail to induce proper expression of Tet enzymes required for 5-hydroxymethylation in 2i-culture conditions. As a result, 5-hydroxymethylation of methylated cystosine residues is impaired. Indeed, we demonstrate that Tet1 and Tet2 are mRNA targets of Dazl, indicating that Dazl might play a role in protection or stabilizing these mRNA molecules. Our results provide insight in the regulation of the acquisition of naïve pluripotency and demonstrate that Dazl is required for TET-mediated cytosine hydroxymethylation in cells that are actively reprogramming to a pluripotent ground state. RNA-IP experiments were used to identify the RNA species bound to DAZL.
Project description:Embryonic stem cell (ESC) cultures display a heterogeneous gene expression profile, ranging from a pristine naïve pluripotent state to a primed epiblast state. While it is known that the addition of inhibitors of GSK3? and MEK (so-called 2i conditions) push ESC cultures towards a more homogeneous naïve pluripotent state, the molecular underpinnings of this naïve transition are not completely understood. Here we demonstrate that Dazl, a RNA-binding protein previously thought to be expressed specifically in developing primordial germ cells (PGCs), marks a subpopulation of ESCs in vitro that is actively transitioning toward naïve pluripotency. In the absence of Dazl expression, ESCs fail to induce proper expression of Tet enzymes required for 5-hydroxymethylation in 2i-culture conditions. As a result, 5-hydroxymethylation of methylated cystosine residues is impaired. Indeed, we demonstrate that Tet1 and Tet2 are mRNA targets of Dazl, indicating that Dazl might play a role in protection or stabilizing these mRNA molecules. Our results provide insight in the regulation of the acquisition of naïve pluripotency and demonstrate that Dazl is required for TET-mediated cytosine hydroxymethylation in cells that are actively reprogramming to a pluripotent ground state. Two independent mouse ES cell lines, Dazl-GFP and Stella-GFP, were cultured on ?-irradiated feeder MEFs in DMEM containing 15% FBS or serum-free B27N2 medium both supplemented with leukemia inhibitory factor (LIF) (Ying 2008). For the 2i experiments, 1µM MEK inhibitor PD0325901 (Axon Medchem), and 5 µM GSK3? inhibitor Kenpaullone (Tocris), were used. Cells were harvest at 0, 3 and 10 days in each condition for expression microarray analysis.
Project description:Primordial germ cells (PGCs) are the embryonic precursors to egg and sperm. When removed from the embryonic gonad, PGCs can give rise to embryonic germ cell lines (EGs), pluripotent stem cells that display most of the characteristics of embryonic stem cells (ESCs) including the ability to form teratomas and to contribute to chimera formation. In mice, EG cells can be derived between E8.5 up to E12.5 of embryonic development, at which point the PGCs undergo sexual differentiation and in the male transition into unipotent gonocytes. Dazl, a germ cell-specific RNA-binding protein, is specifically expressed in developing PGCs and is required for proper germ cell development. Dazl knockout mice are infertile, but the molecular mechanisms underlying this phenotype are still unknown. Here we demonstrate that Dazl localizes in granular structures in mammalian PGCs but not in ESCs. We demonstrate Dazl plays a central role in a large mRNA/protein interactive network that includes members of Fragile-X family RNA-binding proteins. We demonstrate that Dazl and Fxr1 play a central role in these granules and directly regulate the translation of specific core pluripotency factors, including Sox2 and Suz12. Global gene expression changes following Dazl knockdown in in vitro primordial germ cells. In vitro primordial germ cells carrying control and Dazl knockdown shRNAs were generated from Oct4-GFP ES cells and isolated by FACS analysis. The global gene expression profiles were analyzed by Agilent Mouse Whole Genome 4X44K one-color microarrays.
Project description:Primordial germ cells (PGCs) are the embryonic precursors to egg and sperm. When removed from the embryonic gonad, PGCs can give rise to embryonic germ cell lines (EGs), pluripotent stem cells that display most of the characteristics of embryonic stem cells (ESCs) including the ability to form teratomas and to contribute to chimera formation. In mice, EG cells can be derived between E8.5 up to E12.5 of embryonic development, at which point the PGCs undergo sexual differentiation and in the male transition into unipotent gonocytes. Dazl, a germ cell-specific RNA-binding protein, is specifically expressed in developing PGCs and is required for proper germ cell development. Dazl knockout mice are infertile, but the molecular mechanisms underlying this phenotype are still unknown. Here we demonstrate that Dazl localizes in granular structures in mammalian PGCs but not in ESCs. We demonstrate Dazl plays a central role in a large mRNA/protein interactive network that includes members of Fragile-X family RNA-binding proteins. We demonstrate that Dazl and Fxr1 play a central role in these granules and directly regulate the translation of specific core pluripotency factors, including Sox2 and Suz12. Global gene expression changes during in vitro germ cell differentiation from murine ES cells and comparison to in vivo germ cells. In vitro primordial germ cells differentiated from Stella-GFP ES cells and Dazl-GFP ES cells. The GFP-positive cells were isolated by FACS analysis. Dazl-GFP+ cells were isolated from transgenic E13.5 embryonic gonads and P7-P11 juvenile mouse testes. The global gene expression profiles were analyzed by Agilent Mouse Whole Genome 4X44K one-color microarrays. Two replicates per condition.
Project description:Primordial germ cells (PGCs) are the embryonic precursors to egg and sperm. When removed from the embryonic gonad, PGCs can give rise to embryonic germ cell lines (EGs), pluripotent stem cells that display most of the characteristics of embryonic stem cells (ESCs) including the ability to form teratomas and to contribute to chimera formation. In mice, EG cells can be derived between E8.5 up to E12.5 of embryonic development, at which point the PGCs undergo sexual differentiation and in the male transition into unipotent gonocytes. Dazl, a germ cell-specific RNA-binding protein, is specifically expressed in developing PGCs and is required for proper germ cell development. Dazl knockout mice are infertile, but the molecular mechanisms underlying this phenotype are still unknown. Here we demonstrate that Dazl localizes in granular structures in mammalian PGCs but not in ESCs. We demonstrate Dazl plays a central role in a large mRNA/protein interactive network that includes members of Fragile-X family RNA-binding proteins. We demonstrate that Dazl and Fxr1 play a central role in these granules and directly regulate the translation of specific core pluripotency factors, including Sox2 and Suz12. RNA species interacting specifically with Dazl in primordial germ cells were identified by RNA-IP microarray analysis. This dataset contains data from native RNA-IPs without UV-crosslinking. Two independent native RNA-IP (anti-V5 and anti-GFP) experiments from in vitro derived primordial germ cells expressing Dazl-GFP-V5. Input Total RNA and mock IP using normal mouse IgG were used as controls. Control and IP-enriched RNA samples were analyzed by Agilent Mouse Whole Genome 4X44K one-color microarrays.
Project description:Primordial germ cells (PGCs) are the embryonic precursors to egg and sperm. When removed from the embryonic gonad, PGCs can give rise to embryonic germ cell lines (EGs), pluripotent stem cells that display most of the characteristics of embryonic stem cells (ESCs) including the ability to form teratomas and to contribute to chimera formation. In mice, EG cells can be derived between E8.5 up to E12.5 of embryonic development, at which point the PGCs undergo sexual differentiation and in the male transition into unipotent gonocytes. Dazl, a germ cell-specific RNA-binding protein, is specifically expressed in developing PGCs and is required for proper germ cell development. Dazl knockout mice are infertile, but the molecular mechanisms underlying this phenotype are still unknown. Here we demonstrate that Dazl localizes in granular structures in mammalian PGCs but not in ESCs. We demonstrate Dazl plays a central role in a large mRNA/protein interactive network that includes members of Fragile-X family RNA-binding proteins. We demonstrate that Dazl and Fxr1 play a central role in these granules and directly regulate the translation of specific core pluripotency factors, including Sox2 and Suz12. RNA species interacting specifically with Dazl in primordial germ cells were identified by RNA-IP microarray analysis. This dataset contains data from UV-crosslinked RNA-IPs from in vitro PGC lysates. UV-crosslinked RNA-IP (anti-GFP and anti-PABP1) experiments from in vitro derived primordial germ cells expressing Dazl-GFP-V5. Input Total RNA and polyA-binding protein 1 (PABP1) IP were used as controls. Control and IP-enriched RNA samples were analyzed by Agilent Mouse Whole Genome 4X44K one-color microarrays. Two replicates for each condition were done.
Project description:Following implantation, mouse epiblast cells transit from a naïve to a primed state in which they are competent for both somatic and primordial germ cell (PGC) specification. Using mouse embryonic stem cells (mESC) as an in vitro model to study the transcriptional regulatory principles orchestrating peri-implantation development, here we show that the transcription factor Foxd3 is necessary for the exit from naïve pluripotency and the progression to a primed pluripotent state. During this transition, Foxd3 acts as a repressor that dismantles a significant fraction of the naïve pluripotency expression program through the decommissioning of active enhancers associated with key naïve pluripotency and early germline genes. Subsequently, Foxd3 needs to be silenced in primed pluripotent cells to allow the reactivation of relevant genes required for proper PGC specification. Our findings uncover a wave of activation-deactivation of Foxd3 as a crucial step for the exit from naïve pluripotency and subsequent PGC specification. mRNA profiles were generated by RNA-seq in duplicates for each of the following mESC lines: Foxd3fl/fl;Cre-ER mESC maintained in "Serum+LIF" (SL) treated with TM for three days (SL Foxd3-/-); untreated Foxd3fl/fl;Cre-ER SL mESC (SL Foxd3fl/fl); tetON Foxd3 SL mESC treated with Dox for three days; WT SL mESC treated with Dox for three days; Foxd3fl/fl;Cre-ER mESC maintained in "2i+LIF" (2i) treated with TM for three days (2i Foxd3-/-); untreated Foxd3fl/fl;Cre-ER 2i mESC (2i Foxd3fl/fl).
Project description:Naïve and primed pluripotency is characterized by distinct signaling requirements, transcriptomes and developmental properties, but both cellular states share key transcriptional regulators, Oct4, Sox2 and Nanog. Here we demonstrate that transition between these two pluripotent states is associated with widespread Oct4 relocalization, mirrored by global rearrangement of enhancer chromatin landscapes. Our genomic and biochemical analyses identified candidate mediators of primed state-specific Oct4 binding, including Otx2 and Zic2/3. Even in the absence of other differentiation cues, premature Otx2 overexpression is sufficient to exit the naïve state, induce transcription of a large subset of primed pluripotency-associated genes and redirect Oct4 to thousands of previously inaccessible sites. However, ability of Otx2 to engage new enhancer regions is determined by its levels, cis-encoded properties of the sites and signaling environment. Our results illuminate regulatory mechanisms underlying pluripotency and suggest that capacity of transcription factors such as Otx2 and Oct4 to function as pioneers is highly context-dependent ChIP-seq analysis was performed to map enhancers and associated transcription factors. We used H3K27ac, H3K4me1 and p300 to call enhancers from 2 different pluripotent cell states: ESC and EpiLC. In addition we performed ChIP-seq for Oct4 and Otx2 from these cell states. All these experiments were carried out in replicates, for the EpiLC state the replicates were performed with and without ActivinA. Additionally we carried out ChIPseq for Otx2 and Oct4 in Otx2ko cell lines in which we integrated an inducible Otx2 gene before and after induction with doxycycline.
Project description:Naïve and primed pluripotency is characterized by distinct signaling requirements, transcriptomes and developmental properties, but both cellular states share key transcriptional regulators, Oct4, Sox2 and Nanog. Here we demonstrate that transition between these two pluripotent states is associated with widespread Oct4 relocalization, mirrored by global rearrangement of enhancer chromatin landscapes. Our genomic and biochemical analyses identified candidate mediators of primed state-specific Oct4 binding, including Otx2 and Zic2/3. Even in the absence of other differentiation cues, premature Otx2 overexpression is sufficient to exit the naïve state, induce transcription of a large subset of primed pluripotency-associated genes and redirect Oct4 to thousands of previously inaccessible sites. However, ability of Otx2 to engage new enhancer regions is determined by its levels, cis-encoded properties of the sites and signaling environment. Our results illuminate regulatory mechanisms underlying pluripotency and suggest that capacity of transcription factors such as Otx2 and Oct4 to function as pioneers is highly context-dependent transcription profile of ESCs and EpiLCs to analzye changes during differentiation and the effect of Otx2 loss and overexpression on the differentiation properties