Cells adapt to environmental changes, including fluctuations in oxygen levels, through the induction of specific gene expression programs. To identify genes regulated by hypoxia at the transcriptional level, we pulse-labeled HUVEC cells with 4-thiouridine and sequenced nascent transcripts. Then, we searched genome-wide binding profiles from the ENCODE project for factors that correlated with changes in transcription and identified binding of several components of the Sin3A co-repressor complex, including SIN3A, SAP30 and HDAC1/2, proximal to genes repressed by hypoxia. SIN3A interference revealed that it participates in the downregulation of 75% of the hypoxia-repressed genes in endothelial cells. Unexpectedly, it also blunted the induction of 47% of the upregulated genes, suggesting a role for this corepressor in gene induction. In agreement, ChIP-seq experiments showed that SIN3A preferentially localizes to the promoter region of actively transcribed genes and that SIN3A signal was enriched in hypoxia-repressed genes, prior exposure to the stimulus. Importantly, SINA3 occupancy was not altered by hypoxia in spite of changes in H3K27ac signal. In summary, our results reveal a prominent role for SIN3A in the transcriptional response to hypoxia and suggest a model where modulation of the associated histone deacetylase activity, rather than its recruitment, determines the transcriptional output. Overall design: Exponentially growing non-synchronized HUVEC were exposed to normoxia or hypoxia (21% or 1% oxygen respectively) for 8 hours and pulse-labelled with 4-thiouridine during the last two hours of treatment. RNA was extracted from samples in each condition (total RNA) and an aliquot was subjected to affinity chromatography to purify the 4-thiouridine-labelled (newly transcribed RNA, Newly Tr) and non-labelled (Pre-existent) RNA fractions. All three RNA fractions (total, newly transcribed and pre-existent) from each sample were analyzed by high-throughput sequencing. Submission includes 12 samples corresponding to 3 independent biological replicates.
The SIN3A histone deacetylase complex is required for a complete transcriptional response to hypoxia.
Cell line, Treatment, Subject
View SamplesCells adapt to environmental changes, including fluctuations in oxygen levels, through the induction of specific gene expression programs. To identify genes regulated by hypoxia at the transcriptional level, we pulse-labeled HUVEC cells with 4-thiouridine and sequenced nascent transcripts. Then, we searched genome-wide binding profiles from the ENCODE project for factors that correlated with changes in transcription and identified binding of several components of the Sin3A co-repressor complex, including SIN3A, SAP30 and HDAC1/2, proximal to genes repressed by hypoxia. SIN3A interference revealed that it participates in the downregulation of 75% of the hypoxia-repressed genes in endothelial cells. Unexpectedly, it also blunted the induction of 47% of the upregulated genes, suggesting a role for this corepressor in gene induction. In agreement, ChIP-seq experiments showed that SIN3A preferentially localizes to the promoter region of actively transcribed genes and that SIN3A signal was enriched in hypoxia-repressed genes, prior exposure to the stimulus. Importantly, SINA3 occupancy was not altered by hypoxia in spite of changes in H3K27ac signal. In summary, our results reveal a prominent role for SIN3A in the transcriptional response to hypoxia and suggest a model where modulation of the associated histone deacetylase activity, rather than its recruitment, determines the transcriptional output. Overall design: Exponentially growing non-synchronized HUVEC were transduced with lentiviral particles encoding for shRNA targeting EPAS1 or control shRNA. 72h after infection, cells were exposed to normoxia or hypoxia (21% or 1% oxygen respectively) for 8 hours and pulse-labelled with 4-thiouridine during the last two hours of treatment. RNA was extracted from samples in each condition (total RNA) and an aliquot subjected to affinity chromatography to purify the 4-thiouridine-labelled RNA fraction (newly transcribed RNA, Newly Tr). Both RNA fractions from each condition were analyzed by high-throughput sequencing. Data includes 8 samples from a single biological replicate.
The SIN3A histone deacetylase complex is required for a complete transcriptional response to hypoxia.
Cell line, Subject
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Deregulated sex chromosome gene expression with male germ cell-specific loss of Dicer1.
Sex, Specimen part
View SamplesMicroRNAs (miRNAs) are a class of endogenous, non-coding RNAs that mediate post-transcriptional gene silencing by inhibiting mRNA translation and promoting mRNA decay. DICER1, an RNAse III endonuclease encoded by Dicer1, is required for processing short 21-22 nucleotide miRNAs from longer double-stranded RNA precursors. Here, we investigate the loss of Dicer1 in mouse postnatal male germ cells to determine how disruptions in the miRNA biogenesis pathway may contribute to infertility. Reduced levels of Dicer1 transcripts and DICER1 were confirmed in germ cell knock-out (GCKO) testes by postnatal day 18 (P18). Compared to wild-type (WT) at 8 weeks, GCKO males had no change in body weight, yet showed significant reductions in testis mass and sperm number. Histology and fertility tests confirmed spermatogenic failure in GCKO males. Array analyses at P18 showed 96% of miRNA genes were down-regulated and 37% of protein-coding genes were differentially expressed in GCKO testes. Interestingly, we observed preferential overexpression of genes on the sex chromosomes in GCKO testes, with more than 80% of the genes overlapping those proposed to undergo meiotic sex chromosome inactivation (MSCI) in the germ cells. Compared to WT, GCKO mice showed higher percentages of cells at early meiotic stages (leptotene and zygotene) but lower percentages at later stages (pachytene, diplotene and metaphase I), providing evidence that deletion of Dicer1 leads to disruptions in meiotic progression. Furthermore, we observed fewer elongating spermatids with proper translational activation of transition protein 2 (Tnp2), protamine 1 and 2 (Prm1 and Prm2) in GCKO testes after step 12-14. Therefore, deleting Dicer1 in early postnatal germ cells causes misregulation of transcripts encoded by genes on the sex chromosomes, impairs meiotic progression and post-meiotic translational control and results in spermatogenic failure and infertility.
Deregulated sex chromosome gene expression with male germ cell-specific loss of Dicer1.
Sex, Specimen part
View SamplesBackground: Malignant peripheral nerve sheath tumors (MPNST) are soft-tissue sarcomas that can arise either sporadically or in association with neurofibromatosis type 1 (NF1). These aggressive malignancies confer poor survival, with no effective therapy available.
Comprehensive establishment and characterization of orthoxenograft mouse models of malignant peripheral nerve sheath tumors for personalized medicine.
Disease
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Stem cell-like transcriptional reprogramming mediates metastatic resistance to mTOR inhibition.
Specimen part, Cell line
View SamplesInhibitors of the mechanistic target of rapamycin (mTOR) are currently used to treat advanced metastatic breast cancer. However, whether an aggressive phenotype is sustained through adaptation or resistance to mTOR inhibition remains unknown. Here, complementary studies in human tumors, cancer models and cell lines reveal transcriptional reprogramming that supports metastasis in response to mTOR inhibition. This cancer feature is driven by EVI1 and SOX9. EVI1 functionally cooperates with and positively regulates SOX9, and promotes the transcriptional upregulation of key mTOR pathway components (REHB and RAPTOR) and of lung metastasis mediators (FSCN1 and SPARC). The expression of EVI1 and SOX9 is associated with stem cell-like and metastasis signatures, and their depletion impairs the metastatic potential of breast cancer cells. These results establish the mechanistic link between resistance to mTOR inhibition and cancer metastatic potential, thus enhancing our understanding of mTOR targeting failure.
Stem cell-like transcriptional reprogramming mediates metastatic resistance to mTOR inhibition.
Specimen part
View SamplesWe are studying signaling pathways and growth properties of cultured human ovarian cancer cells that are expressing the G protein-coupled receptor, luteinizing hormone receptor (LHR),particularly interested in the changes that occur when the receptor is activated by its cognate ligand, gonadotropin (LH). To investigate these questions, we have employed the SKOV3 ovarian cancer cell line that has been stably transfected with LHR, and can then test the response of these cells in culture following exposure to LH.
Regulation of gene expression in ovarian cancer cells by luteinizing hormone receptor expression and activation.
Cell line, Treatment, Time
View SamplesThe glycopeptide antibiotic vancomycin (VCM) represents one of the last lines of defense against methicillin-resistant Staphylococcus aureus infections. However, vancomycin is nephrotoxic, but the mechanism of toxicity is still unclear.
Gene expression analysis reveals new possible mechanisms of vancomycin-induced nephrotoxicity and identifies gene markers candidates.
Specimen part
View SamplesWe describe a new mutant allele of the ACTIN2 gene with enhanced actin dynamics, displaying a broad array of twisting and bending phenotypes that resemble BR-treated plants. Moreover, auxin transcriptional regulation is enhanced on the mutant background, supporting the idea that shaping actin filaments is sufficient to modulate BR-mediated auxin responsiveness. The actin cytoskeleton thus functions as a scaffold for integration of auxin and BR signaling pathways.
Role of actin cytoskeleton in brassinosteroid signaling and in its integration with the auxin response in plants.
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