Targeted DamID reveals differential binding of mammalian pluripotency factors
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ABSTRACT: The precise control of gene expression by transcription factor networks is critical to organismal development. The predominant approach for mapping transcription factor-chromatin interactions has been chromatin immunoprecipitation (ChIP). However, ChIP requires a large number of homogeneous cells and antisera with high specificity. A second approach, DamID, has the drawback that high levels of Dam methylase are toxic. Here we modify our Targeted DamID approach (TaDa) to enable cell type-specific expression in mammalian systems, generating an inducible system (mammalian TaDa or MaTaDa) to identify protein/DNA interactions in 100 to 1000 times fewer cells than ChIP. We mapped the binding sites of key pluripotency factors, OCT4 and PRDM14, in mouse embryonic stem cells, epiblast-like cells and primordial germ cell-like cells (PGCLCs). PGCLCs are an important system to elucidate primordial germ cell development in mice. We monitored PRDM14 binding during the specification of PGCLCs, identifying direct targets of PRDM14 that are key to understanding its critical role in PGCLC development. We show that MaTaDa is a sensitive and accurate method to assess cell type specific transcription factor binding in limited numbers of cells.
Project description:The germ cell lineage ensures the continuity of life through the generation of male and female gametes, which unite to form a totipotent zygote. We have established a culture system that recapitulates the mouse germ-cell specification pathway: Using cytokines, embryonic stem cells (ESCs)/induced pluripotent stem cells (iPSCs) are induced into epiblast-like cells (EpiLCs) and then into primordial germ cell-like cells (PGCLCs) with capacity both for spermatogenesis and oogenesis, creating an opportunity for understanding and regulating mammalian germ cell development in both sexes in vitro. Here we show that, without cytokines, simultaneous over-expression of three transcription factors (TFs), Blimp1 (also known as Prdm1), Prdm14 and Tfap2c (also known as AP2γ), directs EpiLCs, but not ESCs, swiftly and highly efficiently into a PGC state with endogenous transcription circuitry. The induction of the PGC state on EpiLCs minimally requires Prdm14 but not Blimp1 or Tfap2c. The TF-induced PGC state reconstitutes key transcriptome and epigenetic reprogramming in PGCs, but bypasses a mesodermal program that accompanies PGC specification in vivo and in vitro by cytokines including BMP4. Importantly, the TF-induced PGC-like cells robustly contribute to spermatogenesis and fertile offspring. Our findings provide not only a novel insight into the transcriptional logic that creates a germ cell state, but also a foundation for the TF-based reconstitution and regulation of mammalian gametogenesis. Aim of this analysis is characterization of transcription factor-induced primordial germ cells (TF-PGCLCs) compared with cytokine-induced primordial germ cells (Ck-PGCLCs) (Hayashi et al., 2011, Cell), epiblast-like cells (EpiLCs) (Hayashi et al., 2011, Cell), and embryonic stem cells (ESCs) and identification of genes differentially expressed among them. TF-PGCLCs induced by multiple combinations of TFs (Blimp1 (B), Prdm14 (P14), and Tfap2c (A) (BP14A), BP14, P14A, P14) on day 2 and 4 (for BP14A cells) of the induction were also compared. Parental clone without exogenous TFs cultured with doxycycline, are also included as a negative control. Ck-PGCLCs day 2 and day 4 samples, which are previously unreported, EpiLCs and ESCs used in this study were also included. Overexpression of exogenous three TFs in ESCs yields stella-ECFP (SC) positive cells, which were sorted and included in the analysis. cDNA samples, prepared from approximately 20,000 cells, were amplified with a quantitative global PCR method (Kurimoto et al., 2006, Nucleic Acids Research). Two biological duplicates for each cell type were analyzed. Samples from GSE30056 were also included and reanalysed (GSM1070855-GSM1070864).
Project description:Nanog, a core pluripotency factor in the inner cell mass of blastocysts, is also expressed in unipotent primordial germ cells (PGC) in mice1, where its precise role is yet unclear2-4. We investigated this in an in vitro model, where naïve pluripotent embryonic stem cells (ESCs) cultured in bFGF/ActivinA develop as epiblast-like cells (EpiLCs), and gain competence for PGC-like fate5. Consequently, bone morphogenetic protein (BMP4), or ectopic expression of key germline transcription factors Prdm1/ Prdm14/ Tfap2c, directly induce PGC-like cells (PGCLCs) in EpiLCs, but not in ESCs6-8. Here we report an unexpected discovery that Nanog alone can induce PGCLCs in EpiLCs, independently of BMP4. We propose that following the dissolution of the naïve ESC pluripotency network during establishment of EpiLCs9,10, the epigenome is reset for cell fate determination. Indeed, we found genome-wide changes in NANOG binding pattern between ESCs and EpiLCs, indicating epigenetic resetting of regulatory elements. Accordingly, we show that NANOG can bind and activate enhancers of Prdm1 and Prdm14 in EpiLCs in vitro; BLIMP1 (encoded by Prdm1) then directly induces Tfap2c. Furthermore, while SOX2 and NANOG promote the pluripotent state in ESCs, they show contrasting roles in EpiLCs since Sox2 specifically represses PGCLC induction by Nanog. This study demonstrates a broadly applicable mechanistic principle for how cells acquire competence for cell fate determination, resulting in the context-dependent roles of key transcription factors during development. To characterize Nanog-induced Primordial Germ cell-like cells (PGCLCs), we performed expression analysis of Nanog-induced Day4 PGCLCs compared to male mouse Embryonic Stem Cells (mESCs) and male Day4 PGCLCs which were induced by cytokines. mESCs were maintained in N2B27 2i(CHIR99021 3 µM, PD0325901 1 µM) LIF(1000 U/ml) medium and Day4 PGCLCs were induced in GK15 medium with Nanog induction (0.7 µg/ml) or cytokines (BMP4 500 ng/ml, BMP8A 500 ng/ml, SCF 100 ng/ml, EGF 50 ng/ml and LIF 1000U/ml) as previously reported (Hayashi K et al., Cell, 2011).
Project description:The germ cell lineage ensures the continuity of life through the generation of male and female gametes, which unite to form a totipotent zygote. We have established a culture system that recapitulates the mouse germ-cell specification pathway: Using cytokines, embryonic stem cells (ESCs)/induced pluripotent stem cells (iPSCs) are induced into epiblast-like cells (EpiLCs) and then into primordial germ cell-like cells (PGCLCs) with capacity both for spermatogenesis and oogenesis, creating an opportunity for understanding and regulating mammalian germ cell development in both sexes in vitro. Here we show that, without cytokines, simultaneous over-expression of three transcription factors (TFs), Blimp1 (also known as Prdm1), Prdm14 and Tfap2c (also known as AP2?), directs EpiLCs, but not ESCs, swiftly and highly efficiently into a PGC state with endogenous transcription circuitry. The induction of the PGC state on EpiLCs minimally requires Prdm14 but not Blimp1 or Tfap2c. The TF-induced PGC state reconstitutes key transcriptome and epigenetic reprogramming in PGCs, but bypasses a mesodermal program that accompanies PGC specification in vivo and in vitro by cytokines including BMP4. Importantly, the TF-induced PGC-like cells robustly contribute to spermatogenesis and fertile offspring. Our findings provide not only a novel insight into the transcriptional logic that creates a germ cell state, but also a foundation for the TF-based reconstitution and regulation of mammalian gametogenesis. Aim of this analysis is identification of genes whose expression was altered by each of key transcription factor for transcription factor-induced primordial germ cells (TF-PGCLCs) induction (Blimp1 (B), Prdm14 (P14), and Tfap2c (A)). Both of epiblast-like cells (EpiLCs) (Hayashi et al., 2011, Cell) and aggregates of EpiLCs cultured with doxycycline on day 1 were harvested for 5 cell lines, including BP14A (Clone #3-3), B (#2-4), P14 (#7-109), A (#8-2), and the parental clone (BVSCR26rtTA embryonic stem cells). Total RNA was isolated and analyzed. Two biological duplicates for each cell type were included.
Project description:Nanog, a core pluripotency factor in the inner cell mass of blastocysts, is also expressed in unipotent primordial germ cells (PGC) in mice1, where its precise role is yet unclear2-4. We investigated this in an in vitro model, where naïve pluripotent embryonic stem cells (ESCs) cultured in bFGF/ActivinA develop as epiblast-like cells (EpiLCs), and gain competence for PGC-like fate5. Consequently, bone morphogenetic protein (BMP4), or ectopic expression of key germline transcription factors Prdm1/ Prdm14/ Tfap2c, directly induce PGC-like cells (PGCLCs) in EpiLCs, but not in ESCs6-8. Here we report an unexpected discovery that Nanog alone can induce PGCLCs in EpiLCs, independently of BMP4. We propose that following the dissolution of the naïve ESC pluripotency network during establishment of EpiLCs9,10, the epigenome is reset for cell fate determination. Indeed, we found genome-wide changes in NANOG binding pattern between ESCs and EpiLCs, indicating epigenetic resetting of regulatory elements. Accordingly, we show that NANOG can bind and activate enhancers of Prdm1 and Prdm14 in EpiLCs in vitro; BLIMP1 (encoded by Prdm1) then directly induces Tfap2c. Furthermore, while SOX2 and NANOG promote the pluripotent state in ESCs, they show contrasting roles in EpiLCs since Sox2 specifically represses PGCLC induction by Nanog. This study demonstrates a broadly applicable mechanistic principle for how cells acquire competence for cell fate determination, resulting in the context-dependent roles of key transcription factors during development. Nanog ChIP-seq
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.
Project description:Nanog, a core pluripotency factor in the inner cell mass of blastocysts, is also expressed in unipotent primordial germ cells (PGC) in mice1, where its precise role is yet unclear2-4. We investigated this in an in vitro model, where naïve pluripotent embryonic stem cells (ESCs) cultured in bFGF/ActivinA develop as epiblast-like cells (EpiLCs), and gain competence for PGC-like fate5. Consequently, bone morphogenetic protein (BMP4), or ectopic expression of key germline transcription factors Prdm1/ Prdm14/ Tfap2c, directly induce PGC-like cells (PGCLCs) in EpiLCs, but not in ESCs6-8. Here we report an unexpected discovery that Nanog alone can induce PGCLCs in EpiLCs, independently of BMP4. We propose that following the dissolution of the naïve ESC pluripotency network during establishment of EpiLCs9,10, the epigenome is reset for cell fate determination. Indeed, we found genome-wide changes in NANOG binding pattern between ESCs and EpiLCs, indicating epigenetic resetting of regulatory elements. Accordingly, we show that NANOG can bind and activate enhancers of Prdm1 and Prdm14 in EpiLCs in vitro; BLIMP1 (encoded by Prdm1) then directly induces Tfap2c. Furthermore, while SOX2 and NANOG promote the pluripotent state in ESCs, they show contrasting roles in EpiLCs since Sox2 specifically represses PGCLC induction by Nanog. This study demonstrates a broadly applicable mechanistic principle for how cells acquire competence for cell fate determination, resulting in the context-dependent roles of key transcription factors during development. Refer to individual Series
Project description:The DND microRNA-mediated repression inhibitor 1 (DND1) is a conserved RNA binding protein (RBP) and plays an important role in survival and maintenance of primordial germ cells (PGCs) and the development of the male germline in zebrafish and mice. It was shown to be expressed in human pluripotent stem cells (PSCs), PGCs, and spermatogonia, but little is known about its specific role in pluripotency and human germline development. Here we use CRISPR/Cas mediated knockout and PGC-like cell (PGCLC) differentiation in human iPSCs to analyse if DND1 (1) plays a role in maintaining pluripotency and (2) in specification of PGCLCs. We generated several clonal lines with biallelic loss of function mutations and analysed their potential to differentiate towards PGCLCs and their gene expression on RNA and protein level via bulk RNA sequencing and mass spectrometry. The generated knockout iPSCs showed no differences in pluripotency gene expression, proliferation nor trilineage differentiation potential, but yielded reduced numbers o PGCLCs compared to their parental iPSCs. RNAseq analysis in PGCLCs showed significantly reduced expression of genes associated with cellular developmental processes and cell differentiation in knockout cells, including known markers for PGCs (NANOS3, SOX17, PRDM1, EPCAM) and naïve pluripotency (TFCP2L, DNMT3L).
Project description:To investigate the role of EZH2 in transcription regulation in mouse primordial germ cell like cells (PGCLCs), we isolated Ctrl and Ezh2 KO PGCLCs. Our data demonstrates that EZH2-mediated H3K27me3 is dispensible for transcription regulation in PGCLCs.
Project description:Prdm14 is a critical gene for specifying mouse primordial germ cells (PGCs). The changes in expression in mouse PGCs caused by mutations of the Prdm14 gene were investigated at the single-cell level using microarray analysis.