Project description:To study the mechanisms of pluripotency induction, we compared gene expression in pluripotent embryonic germ cells (EGCs) and unipotent primordial germ cells (PGCs). We found 11 genes ≥1.5-fold overexpressed in EGCs. None of the genes identified were Yamanaka's genes, but instead related to glycolytic metabolism. The prospect of pluripotency induction by cell metabolism manipulation was investigated by hypoxic culturing. We demonstrate that hypoxia alone induces reprogramming in PGCs, giving rise to hypoxia-induced EGC-like cells (hiEGL), which differentiate into cells of the three germ layers in vitro, and contribute to the ICM in vivo, demonstrating pluripotency. The mechanism of hypoxia induction involves HIF1? stabilization and Oct4 deregulation. However, hiEGL cannot be passaged long term. Self-renewal capacity is not achieved by hypoxia likely due to lack of upregulation of c-Myc and Klf4. Gene expression analysis of hypoxia signalling suggests that hiEGLs have not reached the stabilization phase of cell reprogramming. The data suggests that the properties of stemness, pluripotency and selfrenewal, are differentially regulated in primordial germ cell reprogramming induced by hypoxia. 8.5 dpc Oct4-GFP PGCs cultured in hypoxia conditions for 6 days were isolated by FACS. To eliminate the possibility of differences due solely to anaerobic respiration, TGC-10 EGC line was exposed to the hypoxia-mimetic agent Cl2Co at 150 microM for four hours prior to RNA isolation. RNA samples to be analyzed by microarrays were prepared using Qiagen RNeasy columns with on-column DNA digestion. 300 ng of total RNA per sample was used as input into a linear amplification protocol (Tetu-Bio), which involved synthesis of T7-linked double-stranded cDNA and 12 hours of in vitro transcription incorporating biotin-labelled nucleotides. Purified and labeled cRNA was then hybridized for 18h onto MouseRef-8 v2 expression BeadChips (Illumina) following the manufacturer's instructions. After washing, chips were stained with streptavidin-Cy3 (GE Healthcare) and scanned using the iScan reader (Illumina) and accompanying software. Samples were exclusively hybridized as biological replicates. The bead intensities were mapped to gene information using BeadStudio 3.2 (Illumina). Background correction was performed using the Affymetrix Robust Multi-array Analysis (RMA) background correction model. Variance stabilization was performed using the log2 scaling and gene expression normalization was calculated with the method implemented in the lumi package of RBioconductor. Data post-processing and graphics were performed with in-house developed functions in Matlab. Hierarchical clustering of genes and samples was performed with one minus correlation metric and the unweighted average distance (UPGMA) (also known as group average) linkage method. 14 samples were analyzed EG: pluripotent Embryonic Germ Cells (EGCs), 2 replicates hiEGL1: hypoxia-induced EGC-like cells (hiEGL), 2 replicates hiEGL2: hypoxia-induced EGC-like cells (hiEGL), 2 replicates ESCm: Embryonic Stem Cells (ESCs) male, 2 replicates ESCf: Embryonic Stem Cells (ESCs) female, 2 replicates EpiT9: Epiblast Stem Cells T9, 1 replicate EpiE3: Epiblast Stem Cells E3, 1 replicate PGC11.5: unipotent Primordial Germ Cells (PGCs) from dpc 11.5 , 2 replicates
Project description:To study the mechanisms of pluripotency induction, we compared gene expression in pluripotent embryonic germ cells (EGCs) and unipotent primordial germ cells (PGCs). We found 11 genes ≥1.5-fold overexpressed in EGCs. None of the genes identified were Yamanaka's genes, but instead related to glycolytic metabolism. The prospect of pluripotency induction by cell metabolism manipulation was investigated by hypoxic culturing. We demonstrate that hypoxia alone induces reprogramming in PGCs, giving rise to hypoxia-induced EGC-like cells (hiEGL), which differentiate into cells of the three germ layers in vitro, and contribute to the ICM in vivo, demonstrating pluripotency. The mechanism of hypoxia induction involves HIF1? stabilization and Oct4 deregulation. However, hiEGL cannot be passaged long term. Self-renewal capacity is not achieved by hypoxia likely due to lack of upregulation of c-Myc and Klf4. Gene expression analysis of hypoxia signalling suggests that hiEGLs have not reached the stabilization phase of cell reprogramming. The data suggests that the properties of stemness, pluripotency and selfrenewal, are differentially regulated in primordial germ cell reprogramming induced by hypoxia. 8.5 dpc Oct4-GFP PGCs cultured in hypoxia conditions for 6 days were isolated by FACS. To eliminate the possibility of differences due solely to anaerobic respiration, TGC-10 EGC line was exposed to the hypoxia-mimetic agent Cl2Co at 150 microM for four hours prior to RNA isolation. RNA samples to be analyzed by microarrays were prepared using Qiagen RNeasy columns with on-column DNA digestion. 300 ng of total RNA per sample was used as input into a linear amplification protocol (Tetu-Bio), which involved synthesis of T7-linked double-stranded cDNA and 12 hours of in vitro transcription incorporating biotin-labelled nucleotides. Purified and labeled cRNA was then hybridized for 18h onto MouseRef-8 v2 expression BeadChips (Illumina) following the manufacturer's instructions. After washing, chips were stained with streptavidin-Cy3 (GE Healthcare) and scanned using the iScan reader (Illumina) and accompanying software. Samples were exclusively hybridized as biological replicates. The bead intensities were mapped to gene information using BeadStudio 3.2 (Illumina). Background correction was performed using the Affymetrix Robust Multi-array Analysis (RMA) background correction model. Variance stabilization was performed using the log2 scaling and gene expression normalization was calculated with the method implemented in the lumi package of RBioconductor. Data post-processing and graphics were performed with in-house developed functions in Matlab. Hierarchical clustering of genes and samples was performed with one minus correlation metric and the unweighted average distance (UPGMA) (also known as group average) linkage method.
Project description:HIF1α is a key regulator of hypoxia, however, the changes of its target genes in VSMCs under hypoxia were unknown. CoCl2 is a chemical hypoxia agent which leads to the stabilization of HIF1-α and the expression of hypoxia responsive genes, Therefore Hif1afl/fl and Hif1a△SMC VSMCs were treated with CoCl2 and performed microarray analysis. We used microarray to detail the gene expression of WT (Hif1afl/fl) mice and VSMC-specific HIF1α disruption (Hif1a△SMC) mice VSMCs treated with 150μM CoCl2 for 24hours.
Project description:ABL1 kinase inhibitors such as imatinib mesylate (IM) are effective in managing chronic myelogenous leukemia (CML) but incapable of eliminating leukemia stem cells (LSCs), suggesting that kinase−independent pathways support LSC survival. Given that the bone marrow hypoxic microenvironment supports hematopoietic stem cells, we investigated if hypoxia similarly contributes to LSC persistence. Importantly, we found that while BCR−ABL1 kinase remained effectively inhibited by IM under hypoxia, apoptosis became partially suppressed. Furthermore, hypoxia enhanced the clonogenicity of CML cells, as well as their efficiency in repopulating immunodeficient mice, both in the presence and absence of IM. HIF1−α, which is the master regulator of the hypoxia transcriptional response is expressed in the bone marrow specimens of CML individuals. In vitro, HIF1−α is stabilized during hypoxia and its expression and transcriptional activity can be partially attenuated by concurrent IM treatment. Expression analysis demonstrates at the whole transcriptome level that hypoxia and IM regulate distinct subsets of genes. Functionally, knockdown of HIF1−α abolished the enhanced clonogenicity during hypoxia. Taken together, our results suggest that in the hypoxic microenvironment, HIF1−α signaling supports LSC persistence independently of BCR−ABL1 kinase activity. Thus targeting HIF1−α and its pathway components may be therapeutically important for the complete eradication of LSCs.
Project description:VHL is the most frequently mutated gene in ccRCC.It functions via the oxygen-dependent ubiquitin-mediated degradation of hypoxia-inducible factor (HIF). The stabilization and hyperactivation of HIF1 play essential roles in tumorigenesis. This is a TMT based proteomics experiment aimed to investigate the functions of VHL in ccRCC systematically.
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: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:Human primordial germ cells (hPGCs) are the first embryonic progenitors in the germ cell lineage, yet the molecular mechanisms required for hPGC formation are not well characterized. To identify regulatory regions in hPGC development, we used the assay for transposase-accessible chromatin using sequencing (ATAC-seq) to systematically characterize regions of open chromatin in hPGCs and hPGC-like cells (hPGCLCs) differentiated from human embryonic stem cells (hESCs). We discovered regions of open chromatin unique to hPGCs and hPGCLCs that significantly overlap with TFAP2C-bound enhancers identified in the naive ground state of pluripotency. Using CRISPR/Cas9, we show that deleting the TFAP2C-bound naive enhancer at the OCT4 locus (also called POU5F1) results in impaired OCT4 expression and a negative effect on hPGCLC identity.
Project description:Glioblastoma (GBM) is the most common primary malignant cancer of the central nervous system. Hypoxia, low oxygen, has been linked to GBM infiltration and aggressive tumor progression leading to poor patient outcome. Hypoxia-induced pathways are activated by the stabilization of HIF1-α, which upregulates genes related to reprogramming metabolism, angiogenesis, cell trafficking, and cell survival. However, underlying mechanisms of HIF-1α involvement with GBM cell specific pathways is not fully understood. Here, we show that hypoxia can induce specific genes dependent on GBM subtype. In a in vitro migration assay, we screened eight patient-derived GBM stem cell lines. Two lines, UCA and UNB, were found to induce an increased migration ability in response to hypoxia. By RNA bulk sequencing, we identified key specific genes that were upregulated in each cell line that were not shared between them. Furthermore, we found that this data set correlates to previous single-cell RNA sequencing findings of GBM having differentiated transcriptional subtypes. Our results demonstrate how hypoxia induces a specific response in tumor cells by activating genes for survival and tumor progression. Our study forms the basis for future approaches to characterize top candidate genes and elucidate their role in tumor survival in response to hypoxia. Inhibition of these top candidate genes can be a strategy used to dampen hypoxia pro-tumor properties and may lead to better outcomes for GBM patients.
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.