Reduced representation bisulfite sequencing (RRBS) for primordial germ cells and somatic cells during zebrafish early embryogenesis
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ABSTRACT: Zebrafish Primordial Germ Cells (PGCs) and somatic cells were isolated via FACS from Buc-GFP fish strain. Reduced representation bisulfite sequencing (RRBS) was performed on PGCs and somatic cells at high(6000-7000 cells per replicate), dome (7500 cells per replicate)and prim-5 stages(4500-5000 cells per replicate). Two replicates were collected for each cell type and stage.
Project description:Purpose: To identify molecular pathways underlying epigenetic reprogramming in early germ cell precursors, we examined global gene expression of wild type primordial germ cells using mRNA sequencing. Methods: Given the limited number of PGCs collected from E9.5 to E13.5 (ranging from 300 to 5000), we used a low-input RNA sequencing method, Smart-Seq. RNA libraries were pooled and sequenced by Illumina Hiseq. Results: We generated >22 million uniquely mapped reads per sample and identified >10 thousand transcripts per genotype (RPKM>0.1). Hierarchical clustering and correlation analysis on gene expression indicates samples were clearly separated according to their genotypes with Spearman correlation coefficient of 0.98/0.99 within biological replicates. Compared with E9.5 PGCs, 479 genes were significantly up-regulated and 248 genes were down-regulated in E11.5 PGCs. When compared with E11.5 PGCs, male E13.5 PGCs had 362 up-regulated, and 239 down-regulated genes, whereas female E13.5 PGCs had 1163 up-regulated and 333 down-regulated genes. Overall, the number of up-regulated genes was greater than that of the down-regulated genes in every comparison, suggesting that gene expression is generally activated during PGC reprogramming. mRNA profiles of primordial germ cells derived from developmental embryos stages (E9.5, E11.5 and E13.5) were generated by deep sequencing, in duplicates (E9.5 and E11.5) or triplicates (E13.5f and E13.5m), using Illumina Hiseq.
Project description:The small non-coding RNAs (sncRNAs) are considered as postranscriptional key regulators of male germ cell development. In addition to microRNAs (miRNAs) and PIWI-interacting RNAs (piRNAs), other sncRNAs generated from small nucleolar RNAs (snoRNAs), tRNAs or rRNAs processing may also play important regulatory roles in spermatogenesis. By next generation sequencing (NGS), we characterized the different sncRNA populations detected at three milestone stages in male germ differentiation: primordial germ cells (PGCs) at 13.5 dpc, pubertal spermatogonia cells, and mature spermatozoa. In order to assess the potential transmission of the sncRNAs through the mature spermatozoa during fertilization, the sncRNA population detected in male germ cells was also compared with sncRNAs detected in unfertilized mouse oocytes and zygotes. Combining the data obtained by NGS and microarrays from whole PGC and spermatogonia transcriptome, we defined the potential regulatory roles of specific miRNAs and their validated targets. Similar to miRNAs, both the small RNAs derived from snoRNAs and the piRNAs, could be involved in the postranscriptional regulation of mRNA transcripts during the male germ development. Finally, our results strongly suggest that the small RNAs-derived from tRNAs and rRNAs are interacting with PIWI proteins, and specifically with MILI. These new classes of piRNAs are not generated by the ping-pong pathway and could be the source of primary piRNAs. mRNA analysis of Primordial Germ Cells (PGCs), Spermatogonia cells (SPG), adult testis (AdT) and Gonad-less (GL) embryos. Indirect comparisons were made across multiple arrays with raw data pulled from different channels for data analysis and comparison to the control data.
Project description:We developed a ChIP protocol for the analysis of histone marks using less than 10,000 cells per IP, and used it to investigate the chromatin state of E11.5 mouse primordial germ cells (PGCs). A genome-wide ChIP-Seq analysis of E11.5 PGCs revealed a distribution of H3K4me3/H3K27me3 bivalent domains highly enriched for developmental regulatory genes. H3K4me3 and H3K27me3 ChIP-Seq from mouse E11.5 primordial germ cells.
Project description:Zebrafish Primordial Germ Cells (PGCs) were tracked in the Tg(Buc-GFP) line where the germ plasm protein Buc is fused to GFP. GFP-positive cells were isolated via FACS and RNA-seq was performed on polyadenylated transcripts for PGCs and somatic cells at 256-cell, high, dome, 10 somites and prim-5 stages. Two hundred cells were used for each biological replicate.
Project description:In mammals, sex differentiation of primordial germ cells (PGCs) is determined by extrinsic cues from the environment1. In female PGCs, expression of Stimulated by retinoic acid 8 (Stra8) and meiosis are induced in response to retinoic acid (RA) provided by the mesonephroi2-4. Given the widespread role of RA signaling during development8,9, the molecular mechanism specifying the competence of PGCs to timely express Stra8 and enter meiosis are unknown2,10. Here we identify gene dosage dependent roles in PGC development for Ring1 and Rnf2, two central components of the Polycomb Repressive Complex 1 (PRC1)11,13. Both paralogs are essential for PGC development between day 10.5 and 11.5 of gestation. Rnf2 is subsequently required in female PGCs for maintaining high levels of Oct4 and Nanog expression6, and for preventing premature induction of meiotic gene expression and entry into meiotic prophase. Chemical inhibition of RA signaling partially suppresses precocious Oct4 down-regulation and Stra8 activation in Rnf2-deficient female PGCs. Chromatin immunoprecipitation analyses show that Stra8 is a direct target of PRC1 and PRC2 in PGCs. These data demonstrate the importance of PRC1 gene dosage in PGC development and in coordinating the timing of sex differentiation of female PGCs by antagonizing extrinsic RA signaling. Gene expression of mouse primordial germ cells was analysed using RNAseq method. Primodial germ cells were purified from embryos carrying Oct4(-delta-PE)-GFP transgene by FACS.
Project description:In poultry, in vitro derived primordial germ cells (PGCs) represent an important tool for management of genetic resources. However, several studies have highlighted sexual differences exhibited by PGCs through in vitro steps, which may compromise their reproductive capacities. To understand this phenomenon, we compared the proteome of pregonadal chicken male (ZZ) and female (ZW) PGCs expanded in vitro by quantitative proteomic analysis using a GeLC-MS/MS strategy. The proteins found to be differentially abundant in chicken male and female PGCs indicated their early sexual identity. Many of the proteins up-accumulated in male PGCs were encoded by genes strongly enriched in the sexual chromosome Z. This suggests that the known lack of dosage compensation of the transcription of Z-linked genes between sexes persists at protein level in PGCs, and that this may be a key factor of their autonomous sex differentiation. Male and female PGCs up-accumulated protein sets were associated with differential biological processes, and contained proteins biologically relevant for male and female germ cell development respectively. This study presents first evidence on early predetermined sex specific cell fate of chicken PGCs that will help to understand their sexual physiological specificities and enable more precise sex-specific adaptation of in vitro culture conditions.
Project description:The present investigation was to identify the signaling and metabolic pathways of expressed genes by microarray comparison between Primordial Germ Cells (PGCs) and their somatic counterpart, chicken embryonic fibroblasts (CEFs). We identified a total of 2,605 expressed transcripts. Among these, 1,197 were predominantly expressed in PGCs, and 1,408 were predominantly expressed in CEFs. Cell culture and microarray data generation were performed in triplicate. Blood PGCs from E2.5 embryos (N=20 for each replication) and CEFs from E6.5 embryos (N=5 for each replication) were cultured in appropriate culture medium. Total RNA was extracted from cultured PGCs (1,500,000 cells for each replication) and cultured CEFs (6,000,000 cells for each replication) with a Qiagen RNeasy kit. About 5 M-BM-5g of total RNA from each replication was used for labeling. Probe synthesis from total RNA samples, hybridization, detection, and scanning were performed according to standard protocols from Affymetrix.
Project description:Epigenetic reprogramming, characterized by loss of cytosine methylation and histone modifications, occurs during mammalian development in primordial germ cells (PGCs). Here we provide a detailed map of cytosine methylation on a large portion of the genome in developing male and female PGCs isolated from mouse embryos. We mapped DNA methylation in E13.5 PGCs isolated by FACS sorting from Oct4-GFP male and female embryos. As a control, we also mapped DNA methylation in E7.5 epiblasts from wich PGCs derive from. MeDIP and Input samples were hybridized to Nimblegen HD2 MM8 promoter deluxe arrays covering 12 kb of all gene promoters. Experiments were performed in duplicates for E7.5 epiblasts and triplicates for E13.5 PGCs.
Project description:Background: Genes, RNAs, and proteins play important roles during germline development. However, the functions of non-coding RNAs (ncRNAs) on germline development remain unclear in avian species. Recent high-throughput techniques have identified several classes of ncRNAs, including micro RNAs (miRNAs), small-interfering RNAs (siRNAs), and PIWI-interacting RNAs (piRNAs). These ncRNAs are functionally important in the genome, however, the identification and annotation of ncRNAs in a genome is challenging. The aim of this study was to identify different types of small ncRNAs particularly piRNAs, and the role of piRNA pathway genes in the protection of chicken primordial germ cells (PGCs). Results: At first, we performed next-generation sequencing to identify ncRNAs in chicken PGCs, and we performed ab initio predictive analysis to identify putative piRNAs in PGCs. Then, we examined the expression of three repetitive sequence-linked piRNAs and 14 genic-transcript-linked piRNAs along with their linked genes using real-time PCR. All piRNAs and their linked genes were highly expressed in PGCs. Subsequently, we knocked down two known piRNA pathway genes of chicken, PIWI-like protein 1 (CIWI) and 2 (CILI), in PGCs using siRNAs. After knockdown of CIWI and CILI, we examined their effects on the expression of six putative piRNA-linked genes and DNA double-strand breakage in PGCs. The knockdown of CIWI and CILI upregulated chicken repetitive 1 (CR1) element and RAP2B, a member of RAS oncogene family, and increased DNA double-strand breakage in PGCs. Conclusions: Our results increase the understanding of PGC-expressed ncRNAs and the role of piRNA pathway genes in the protection of germ cells. Small ncRNA expression profiling in SSEA-1 positive PGCs, SSEA-1 negative gonadal stromal cells (GSCs), Stage X blastoderms, and chicken embryonic fibroblast (CEFs)
Project description:Genome-wide DNA demethylation, including the erasure of genome imprints, in primordial germ cells (PGCs), is critical as a first step for creating the totipotent epigenome in the germ line. Here, we provide evidence that contrary to the prevailing model involving active DNA demethylation, imprint erasure in mouse PGCs occurs in a manner consistent with replication-coupled passive DNA demethylation: PGCs erase imprints during their rapid proliferation with little de novo as well as maintenance DNA methylation potential and no major chromatin alterations. Our findings necessitate the re-evaluation of and provide novel insights into the mechanism of genome-wide DNA demethylation in PGCs. We performed expression analysis of primordial germ cells (PGCs) at embryonic days 10.5-13.5. Because the number of PGCs available at these stages were low, cDNAs were amplified by the method that we previously published (Kurimoto et al. 2006, NAR 34: e42 (PMID 16547197)). To include analysis of PGC gene expression at E9.5, we re-normalized the data from our E9.5 PGC samples (GSM744103, GSM744104) from our previous publication (Hayashi et al., 2011, Cell 146: 519-32 (PMD 21820164)) together with the data from this submission.