The cellular response to DNA damage is mediated through multiple pathways that regulate and coordinate DNA repair, cell cycle arrest and cell death. We show that the DNA damage response (DDR) induced by ionizing radiation (IR) is coordinated in breast cancer cells by selective mRNA translation mediated by high levels of translation initiation factor eIF4G1. Increased expression of eIF4G1, common in breast cancers, was found to selectively increase translation of mRNAs involved in cell survival and the DDR, preventing autophagy and apoptosis (Survivin, HIF1, XIAP), promoting cell cycle arrest (GADD45a, p53, ATRIP, Chk1) and DNA repair (53BP1, BRCA1/2, PARP, Rfc2-5, ATM, MRE-11, others). Reduced expression of eIF4G1, but not its homolog eIF4G2, greatly sensitizes cells to DNA damage by IR, induces cell death by both apoptosis and autophagy, and significantly delays resolution of DNA damage foci with little reduction of overall protein synthesis. While some mRNAs selectively translated by higher levels of eIF4G1 were found to use internal ribosome entry site (IRES)-mediated alternate translation, most do not. The latter group shows significantly reduced dependence on eIF4E for translation, facilitated by an enhanced requirement for eIF4G1. Increased expression of eIF4G1 therefore promotes specialized translation of survival, growth arrest and DDR mRNAs that are important in cell survival and DNA repair following genotoxic DNA damage.
DNA damage and eIF4G1 in breast cancer cells reprogram translation for survival and DNA repair mRNAs.
Cell line
View SamplesTranslation initiation factors have complex functions in cells which are not yet understood. We show that depletion of initiation factor eIF4GI only modestly reduces overall protein synthesis in cells, but phenocopies nutrient-starvation or inhibition of protein kinase mTOR, a key nutrient sensor. eIF4GI depletion impairs cell proliferation, bioenergetics and mitochondrial activity, thereby promoting autophagy. Translation of mRNAs involved in cell growth, proliferation and bioenergetics were selectively inhibited by reduction of eIF4GI, whereas mRNAs encoding proliferation inhibitors and catabolic pathway factors were increased. Depletion or over-expression of other eIF4G family members did not recapitulate these results. The majority of mRNAs that were translationally impaired with eIF4GI depletion were excluded from polyribosomes due to the presence of multiple upstream open reading frames and low mRNA abundance. These results suggest that the high levels of eIF4GI observed in many breast cancers might act to specifically increase proliferation, prevent autophagy and release tumor cells from control by nutrient sensing.
eIF4GI links nutrient sensing by mTOR to cell proliferation and inhibition of autophagy.
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View SamplesWe have generated transgenic mice with tetracycline-regulated conditional expression of a constitutively active allele of FoxO3 under the control of the forebrain-specific CaMKIIa promoter. In adult animals, there was a reduction of brain weight by 30% and an almost complete loss of the dorsal dentate gyrus with normal cortical layering. Interestingly, the adult mice showed motor hyperactivity and a selective loss of long-term memory with normal spatial learning. We observed enhanced apoptosis starting from day E10.5. Performing microarray expression analyses and Q-PCR validation with E12.5 forebrain RNA, we observed an over-representation of thalamic markers and an under-representation of cortical markers in transgenic as compared to control animals. Immunohistochemical data show a loss of progenitors in the lateral ventricles. Up-regulation of Pik3ip1 as a target gene of FoxO3 could be responsible for the observed increase in apoptosis. The obtained forebrain expression signature is reminiscent of a Pax6 knockdown phenotype showing that expression of this FoxO3 allele during development affected neural progenitor survival and overall brain development. Conclusion: Neural progenitors are vulnerable to constitutively active FoxO3-induced apoptosis.
Expression of constitutively active FoxO3 in murine forebrain leads to a loss of neural progenitors.
Specimen part
View SamplesWe performed RNA-seq on 42 meningioma samples isolated from human patients to characterize the transcriptome of these tumors Overall design: Poly A selected RNA-seq from 42 meningioma samples
Comprehensive Molecular Profiling Identifies FOXM1 as a Key Transcription Factor for Meningioma Proliferation.
Specimen part, Subject
View SamplesWe investigated the nutritional effects on gene expression in sperm cells of F0 boars from a three generation Large White pig feeding experiment. A group of experimental (E) F0 boars were fed a standard diet supplemented with high amounts of methylating micronutrients whereas a control (C) group of F0 boars received a standard diet. These differentially fed F0 boars sired F1 boars which then sired 60 F2 pigs which were investigated in a previous study. The aim of this study was to investigate if the nutrition affects gene expression in sperm cells of differentially fed boars and thus carry information in the form of RNA molecules to the next generation. Four RNA samples from sperm cells of these differentially fed boars were analyzed by RNA-Seq methodology. We found no differential RNA expression in sperm cells of the two groups based on the adjusted P-value > 0.05. Nevertheless, we performed a pathway analysis with 105 genes that differed in gene expression on the level of nominal P-value < 0.05 between the two diet groups. We found a significant number of these differentially expressed genes were enriched for the pathway maps of bacterial infections in cystic fibrosis (CF) airways, glycolysis and gluconeogenesis p.3 and cell cycle_Initiation of mitosis. The GO processes including a significant portion of differentially expressed genes were viral transcription and viral genome expression, viral infectious cycle, cellular protein localization, cellular macromolecule localization, nuclear-transcribed mRNA catabolic process and nonsense-mediated decay. In summary, the results of the pathway analysis are also inconclusive and it is concluded that RNA expression in sperm cells is not significantly affected by extensive supplementation of methylating micronutrients. Consequently, RNA molecules could not be established as epigenetic marks in this feeding experiment. Overall design: Gene expression in sperm cells from differentially fed F0 boars was measured. F0 boars received either a standard diet or a standard diet supplemented with methylating micronutrients. These boars were used to study transgenerational epigenetic inheritance in a three generation pig pedigree. Therefore it was of interest if the diet affects gene expression in sperm cells which could then be transmitted to next generations.
In search of epigenetic marks in testes and sperm cells of differentially fed boars.
Sex, Specimen part, Subject
View SamplesSjgren's syndrome is an autoimmune disease manifesting primarily as dryness of eyes and mouth. In this study, we compared gene expression in PBMCs between age- and gender-matched patients with Sjgren's syndrome (diagnosed by ACR criteria) and healthy controls. Cells were collected in heparinized tubes and PBMCs were prepared using Ficoll.
Expression of the immune regulator tripartite-motif 21 is controlled by IFN regulatory factors.
Specimen part, Disease
View SamplesThe rate of RNA Polymerase II (RNAPII) elongation has an important role in the control of Alternative splicing (AS); however, the in vivo consequences of an altered elongation rate are unknown. Here, we generated mouse embryonic stem cells (ESCs) knocked-in for a slow elongating form of RNAPII. We show that a reduced transcriptional elongation rate results in early embryonic lethality in mice and impairs the differentiation of ESCs into the neural lineage. This is accompanied by changes in splicing and in gene expression in ESCs and along the pathway of neuronal differentiation. In particular, we found a crucial role for RNAPII elongation rate in transcription and splicing of long neuronal genes involved in synapse signaling. The impact of the kinetic coupling of RNAPII elongation rate with AS is more predominant in ESC-differentiated neurons than in pluripotent cells. Our results demonstrate the requirement for an appropriate transcriptional elongation rate to ensure proper gene expression and to regulate AS during development. Overall design: 4sURDB-Seq mouse wt and homozygous Polr2a[R749H] mutant embryonic stem cells in triplicates.
A slow transcription rate causes embryonic lethality and perturbs kinetic coupling of neuronal genes.
Treatment, Subject
View SamplesThe hypothesis was tested that insect meal (IM) as protein source influences intermediary metabolism of growing pigs. To test this, 5-week-old crossbreed pigs were randomly assigned to 3 groups of 10 pigs each with similar body weights (BW) and fed isonitrogenous diets either without (CON) or with 5 % IM (IM5) or 10 % IM (IM10) from Tenebrio molitor L. for 4 weeks and skeletal muscle was analyzed using transcriptomics. Transcriptomics of skeletal muscle revealed a total of 198 transcripts differentially expressed between IM10 and CON.
Comprehensive evaluation of the metabolic effects of insect meal from <i>Tenebrio molitor</i> L. in growing pigs by transcriptomics, metabolomics and lipidomics.
Sex, Specimen part
View SamplesThe hypothesis was tested that insect meal (IM) as protein source influences intermediary metabolism of growing pigs. To test this, 5-week-old crossbreed pigs were randomly assigned to 3 groups of 10 pigs each with similar body weights (BW) and fed isonitrogenous diets either without (CON) or with 5 % IM (IM5) or 10 % IM (IM10) from Tenebrio molitor L. for 4 weeks and liver was analyzed using transcriptomics. Transcriptomics of the liver revealed a total of 166 transcripts differentially expressed between IM10 and CON.
Comprehensive evaluation of the metabolic effects of insect meal from <i>Tenebrio molitor</i> L. in growing pigs by transcriptomics, metabolomics and lipidomics.
Sex, Specimen part
View SamplesHyperactivation of Notch signaling and the cellular hypoxic response are frequently observed in cancers, with increasing reports of connections to tumor initiation and progression. The two signaling mechanisms are known to intersect, but while it is well established that hypoxia regulates Notch signaling, less is known about whether Notch can regulate the cellular hypoxic response. We now report that Notch signaling specifically controls expression of HIF2a, a key mediator of the cellular hypoxic response. Transcriptional upregulation of HIF2a by Notch under normoxic conditions leads to elevated HIF2a protein levels in primary breast cancer cells as well as in human breast cancer, medulloblastoma and renal cell carcinoma cell lines. The elevated level of HIF2a protein was in certain tumor cell types accompanied by down-regulation of HIF1a protein levels, indicating that high Notch signaling may drive a HIF1a-to-HIF2a switch. At the transcriptome level, the presence of HIF2a was required for approximately 21% of all Notch-induced genes: among the 1062 genes that were upregulated by Notch in medulloblastoma cells during normoxia, upregulation was abrogated in 227 genes when HIF2a expression was knocked down by HIF2a siRNA. In conclusion, our data show that Notch signaling affects the hypoxic response via regulation of HIF2a, which may be important for future cancer therapies. Overall design: DAOY-NERT2 cells, +/- Notch induction by Tamoxifen (TMX) for 48 hours, +/- hypoxia (1% O2) treatment for 48 hours, where HIF1a or HIF2a had been knocked down by siRNA, were subjected to RNA sequencing. The quality of the cDNA libraries was tested on an Agilent 2100 bioanalyzer. The libraries were sequenced on an Illumina HiSeq 2000 system, and the reads were aligned to the human genome (assembly hg19) and a transcriptome database (RefSeq and Ensembl) using bowtie. RPKM values were generated using rpkmforgenes.
Notch signaling promotes a HIF2α-driven hypoxic response in multiple tumor cell types.
Specimen part, Subject
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