Project description:Specification of germ cell fate establishes the germline development during early embryogenesis, yet the underlying mechanisms remain largely unknown in humans. Here we focus on the functional roles of the RNA-binding protein (RBP) DND1 in human germline specification. We deleted the whole genomic region of DND1 in human embryonic stem cells (hESCs), based on which we generated human primordial germ cell-like cells (hPGCLCs). Interestingly, we discovered an increased percentage of hPGCLCs induced from DND1 deleted hESCs, suggesting that DND1 may restrict the specification of human germ cell lineage. Mechanistic investigation reveals that DND1 forms a complex with another RBP NANOS3, in which DND1 facilitates the binding of NANOS3 to their target mRNAs. Furthermore, by analyzing the mRNAs bound by DND1 and NANOS3, we identified SOX4 mRNAs as the key downstream factor for DND1 and NANOS3 complex to restrict the induction of hPGCLCs. Interestingly, DND1 and NANOS3 function in processing bodies (P-bodies) to repress the translation of SOX4 mRNAs, where NANOS3 bridges the interaction between DND1 and the translational repressor 4E-T. Altogether, these findings identify the RBPs DND1 and NANOS3 as “break system” to restrict the entry of germ cell fate in humans.
Project description:We knocked out DND1 in human iPSCs and analysed its role in pluripotency and differentiation. We showed that general pluripotency gene expression is not affected, but KO iPSCs differentiate less efficiently towards PGC-like cells and remaining PGCLCs show reduced expression of NANOS3 and PRDM1.
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:DND1 is essential to maintain germ cell identity. Loss of Dnd1 function results in trans-differentiation of germ cells to somatic fates in zebrafish or the formation of teratomas in mice. To explore the mechanistic role of DND1, we recently developed a transgenic mouse line in which a functional fusion protein between DND1 and GFP is expressed from the endogenous locus (Dnd1GFP). Surprisingly, we found that this reporter distinguishes two male germ cell populations (MGCs) during late gestation cell cycle arrest (G0). Most MGCs express low levels of DND1-GFP, but 5-12% of the population express high levels of DND1-GFP. An RNA-seq time course during late gestation revealed that Dnd1 transcript levels as well as transcript levels for multiple epigenetic regulators are 5-10-fold higher in DND1-GFP-hi cells. Furthermore, using antibodies against DND1-GFP for RNA immunoprecipitation (RIP) time course sequencing during late gestation, we identified multiple epigenetic and translational regulators that are binding targets of DND1 during G0. Among these targets are DNA methyltransferases (Dnmts), the enzyme Setdb1 that imposes the nuclear lamina associated repressive histone mark (H3K9me3), five Tudor domain proteins (Tdrds), four actin dependent regulators (Smarcs), and a group of ribosomal and Golgi proteins. These data suggest that DND1 binds to transcripts of a group of epigenetic enzymes and gates their translation during MGC G0 arrest in late gestation.
Project description:We performed single cell RNA-sequencing (scRNA-Seq) of testes from bovine fetuses derived from either CRISPR/Cas9 NANOS3 knockout (KO; NANOS3 -/-) or wildtype control (NANOS3 +/+) embryos. The scRNA-Seq analysis showed a complete loss of primordial germ cells (PGCs) and gonocytes in NANOS3 KO fetal testes, while maintaining the development of somatic support cells.
Project description:To identify germ cell- and somatic cell-specific gene expression profiles, we performed expression microarray analysis of the mouse gonads of the Nanos3+/-, Nanos3-/- female and male embryos from E12.5 to E15.5.
Project description:To identify germ cell- and somatic cell-specific gene expression profiles, we performed expression microarray analysis of the mouse gonads of the Nanos3+/-, Nanos3-/- female and male embryos from E12.5 to E15.5. Biological duplicates were examined at each stage, genotype, and sex for each experiment.
Project description:Analysis of our transcriptome and RNA immunoprecipitation experiments indicate DND1 acts as a positive regulator of chromatin modifiers in male germ cells, linking RNA binding proteins and epigenetic regulation.
Project description:Maintenance and maturation of primordial germ cells is controlled by complex genetic and epigenetic cascades, and disturbances in this network lead to either infertility or malignant aberration. Transcription factor Tcfap2c / TFAP2C has been described to be essential for primordial germ cell maintenance and to be upregulated in several human germ cell cancers. Using global gene expression profiling, we identified genes deregulated upon loss of Tcfap2c in primordial germ cell-like cells. We show that loss of Tcfap2c affects many aspects of the genetic network regulating germ cell biology, such as downregulation maturation markers and induction of markers indicative of somatic differentiation, cell cycle, epigenetic remodeling, and pluripotency associated genes. Chromatin-immunoprecipitation analyses demonstrated binding of Tcfap2c to regulatory regions of deregulated genes (Sfrp1, Dmrt1, Nanos3, c-Kit, Cdk6, Cdkn1a, Fgf4, Klf4, Dnmt3b and Dnmt3l) suggesting that these genes are direct transcriptional targets of Tcfap2c in primordial germ cells. Since Tcfap2c deficient primordial germ cell like cells display cancer related deregulations in epigenetic remodeling, cell cycle and pluripotency control, the Tcfap2c-knockout allele was bred onto 129S2/Sv genetic background. There, mice heterozygous for Tcfap2c develop germ cell cancer with high incidence. Precursor lesions can be observed as early as E16.5 in developing testes displaying persisting expression of pluripotency markers. We further demonstrate, that mice with a heterozygous deletion of the Tcfap2c target gene Nanos3 are also prone to develop teratoma. These data highlight Tcfap2c as a critical and dose-sensitive regulator of germ cell fate. 8 samples were analyzed. Ctrl ESC: Control mouse embryonic stem cells (ESCs), 2 biological rep KO ESC: Tcfap2c knock-out mouse embryonic stem cells (ESCs), 2 biological rep Ctrl PGC: Control mouse primordial germ cells (PGCs), 2 biological rep KO PGC: Tcfap2c knock-out mouse primordial germ cells (PGCs), 2 biological rep
Project description:Primary ovarian insufficiency (POI) is a complex disorder that affects many genes and the underlying molecular mechanisms remain to be fully elucidated. In this study, a homozygous point mutation, c.808C>T, in the DAZL gene of a POI patient was identified. This homozygous variant causes a C-terminal truncation of DAZL and down-regulation of germ-line gene NANOS3 expression, among other dysregulated genes, in human primordial germ cells (hPGCs) in vitro. Mechanistically, we discovered that the truncated DAZL had defects in regulating mRNA translation for NANOS3, VASA, and SYCP3 - all essential for gametogenesis. Additionally, the truncated DAZL showed impaired interaction with Poly(A)-binding proteins (PABPs), a crucial component of the translation initiation complex. At the cellular level, the truncated mutation resulted in increased apoptosis of in vitro hPGCs. Our findings reveal that the c.808C>T mutation in DAZL causes dysregulated expressions of many genes, increases germ cell apoptosis and ultimately leads to POI.