Removal of introns by pre-mRNA splicing is a critical and in some cases rate-limiting step in mammalian gene expression. Deep sequencing of mouse embryonic stem cell RNA revealed many specific internal introns that are significantly more abundant than the other introns within poly(A) selected transcripts; we classify these as “detained” introns (DIs). We identified thousands of DIs flanking both constitutive and alternatively spliced exons in human and mouse cell lines. Drug inhibition of Clk SR-protein kinase activity triggered rapid splicing changes in a specific set of DIs, about half of which showed increased splicing and half increased intron detention, altering the transcript pool of over 300 genes. These data suggest a widespread mechanism by which a nuclear detained pool of mostly processed pre-mRNAs can be rapidly mobilized in response to stress or homeostatic autoregulation. Overall design: v6.5 mouse embryonic stem cells were untreated, treated with the Clk kinase inhibitor KH-CB19, or treated with DMSO as a negative control. Untreated cells were harvested and a single replicate was sequenced using a custom, ligation-based, stranded library preparation protocol. Treated cells were harvested at time 0 and at 2 hours post-treatment, and poly(A)-selected RNA-seq libraries were made from biological duplicates for each treatment/time, barcoded, and sequenced by strand-specific, paired-end sequencing using the Illumina TruSeq kit.
Detained introns are a novel, widespread class of post-transcriptionally spliced introns.
No sample metadata fields
View SamplesWe generated a global analysis of Rbfox2 splicing regulation combined with a highly specific, single nucleotide-resolution Rbfox2 RNA binding map. We found that Rbfox2 regulates the splicing and expression of many previously unknown targets, and particularly a number of RNA binding proteins (RBPs), by modulating alternative splicing coupled-NMD. Based on our observations of RBP-Rbfox2 co-regulation with a polarity predicted by Rbfox2 binding, we propose a model whereby Rbfox2 tunes autoregulatory splicing events to control RBP expression levels and in turn alter their respective splicing networks. Overall design: iCLIP for epitope-tagged Rbfox2 and control untagged Rbfox2; RNAseq of control and Rbfox2 knockdown in mouse embryonic stem cells
Rbfox2 controls autoregulation in RNA-binding protein networks.
No sample metadata fields
View SamplesRecent studies have identified intracellular metabolism as a fundamental determinant of macrophage function. In obesity, proinflammatory macrophages accumulate in adipose tissue and trigger chronic low-grade inflammation, that promotes the development of systemic insulin resistance, yet changes in their intracellular energy metabolism are currently unknown. We therefore set out to study metabolic signatures of adipose tissue macrophages (ATMs) in lean and obese conditions. F4/80-positive ATMs were isolated from obese vs lean mice. High-fat feeding of wild-type mice and myeloid-specific Hif1-/- mice was used to examine the role of hypoxia-inducible factor-1 (HIF-1) in ATMs part of obese adipose tissue. In vitro, bone marrow-derived macrophages were co-cultured with adipose tissue explants to examine adipose tissue-induced changes in macrophage phenotypes. Transcriptome analysis, real-time flux measurements, ELISA and several other approaches were used to determine the metabolic signatures and inflammatory status of macrophages. In addition, various metabolic routes were inhibited to determine their relevance for cytokine production. Transcriptome analysis and extracellular flux measurements of mouse ATMs revealed unique metabolic rewiring in obesity characterised by both increased glycolysis and oxidative phosphorylation. Similar metabolic activation of CD14+ cells in obese individuals was associated with diabetes outcome. These changes were not observed in peritoneal macrophages from obese vs lean mice and did not resemble metabolic rewiring in M1-primed macrophages. Instead, metabolic activation of macrophages was dose-dependently induced by a set of adipose tissue-derived factors that could not be reduced to leptin or lactate. Using metabolic inhibitors, we identified various metabolic routes, including fatty acid oxidation, glycolysis and glutaminolysis, that contributed to cytokine release by ATMs in lean adipose tissue. Glycolysis appeared to be the main contributor to the proinflammatory trait of macrophages in obese adipose tissue. HIF-1, a key regulator of glycolysis, nonetheless appeared to play no critical role in proinflammatory activation of ATMs during early stages of obesity. Our results reveal unique metabolic activation of ATMs in obesity that promotes inflammatory cytokine release. Further understanding of metabolic programming in ATMs will most likely lead to novel therapeutic targets to curtail inflammatory responses in obesity.
Unique metabolic activation of adipose tissue macrophages in obesity promotes inflammatory responses.
Sex, Specimen part
View SamplesUncontrolled microglial activation may lead to development of inflammation-induced brain damage. Here we uncover a ribosome-based mechanism/check point involved in control of the innate immune response and microglial activation. Using an in vivo model-system for analysis of the dynamic translational state of microglial ribosomes with mRNAs as input and newly synthesized peptides as an output, we find a marked dissociation of microglia mRNA and protein networks following innate immune challenge. Highly up-regulated and ribosome-associated mRNAs were not translated resulting in two distinct microglial molecular signatures, a highly specialized pro-inflammatory mRNA and immunomodulatory/homeostatic protein signature. We find that this is due to specific translational suppression of highly expressed mRNAs through a 3UTR-mediated mechanism involving the RNA binding protein SRSF3. This discovery suggests avenues for therapeutic modulation of innate immune response in resident microglia.
Diverging mRNA and Protein Networks in Activated Microglia Reveal SRSF3 Suppresses Translation of Highly Upregulated Innate Immune Transcripts.
Treatment
View SamplesMolecular mechanisms that are responsible for the development of human skin epithelial cells are not completely understood so far. As a consequence, the efficiency to establish a pure skin epithelial cell population from human induced pluripotent stem cells (hiPSC) remains poor. Using an approach including RNA interference and high-throughput imaging of early epithelial cells, we could identify candidate kinases which are involved in skin epithelial differentiation. Among them, we found HIPK4 to be an important inhibitor of this process. Indeed, its silencing increased the amount of generated skin epithelial precursors, increased the amount of generated keratinocytes and improved growth and differentiation of organotypic cultures, allowing for the formation of a denser basal layer and stratification with the expression of several keratins. Our data bring substantial input in the regulation of human skin epithelial differentiation and for improving differentiation protocols from pluripotent stem cells.
An RNAi Screen Reveals an Essential Role for HIPK4 in Human Skin Epithelial Differentiation from iPSCs.
Specimen part, Time
View SamplesWe sought to obtain gene signature specific of high oxidative phsophorylation function.
Chemotherapy-Resistant Human Acute Myeloid Leukemia Cells Are Not Enriched for Leukemic Stem Cells but Require Oxidative Metabolism.
Cell line, Treatment
View SamplesIt has been hypothesized that chemotherapy resistant human acute myeloid leukemia (AML) cells are enriched in an immature phenotype, cellular quiescence and leukemic initiating cells (LICs). However, these hypotheses have never been validated completely in vivo. We have developed a physiologically relevant chemotherapeutic approach with cytosine arabinoside AraC using patient-derived xenograft (PDX) models. AraC-treated AML cells are not consistently enriched for either immature cells or quiescent cells. AraC treatment does not enrich for LICs as measured by limiting dilution in secondary transplantations. Rather chemotherapy resistant cells in vivo have high levels of reactive oxygen species (ROS) and a gene signature consistent with oxidative phosphorylation (OXPHOS). Treatment of human HIGH OXPHOS but not LOW OXPHOS AML cell lines showed chemotherapy resistance in vivo, showing that essential mitochondrial functions make significant contributions to AraC resistance in AML. Accordingly, targeting mitochondrial OXPHOS metabolism through the inhibition of mitochondrial protein synthesis, the electron transfer chain or fatty acid oxidation induced an energetic shift towards LOW OXPHOS and strongly enhanced anti-leukemic effects of AraC in AML cells. These results demonstrate that chemotherapy resistance in AML is not necessarily associated with stemness but is highly dependent on a distinct oxidative metabolism, and that the HIGH OXPHOS gene signature is a robust hallmark of the AraC response in PDX and a promising therapeutic avenue to treat AML residual disease.
Chemotherapy-Resistant Human Acute Myeloid Leukemia Cells Are Not Enriched for Leukemic Stem Cells but Require Oxidative Metabolism.
Specimen part, Disease
View SamplesIt has been hypothesized that chemotherapy resistant human acute myeloid leukemia (AML) cells are enriched in an immature phenotype, cellular quiescence and leukemic initiating cells (LICs). However, these hypotheses have never been validated completely in vivo. We have developed a physiologically relevant chemotherapeutic approach with cytosine arabinoside AraC using patient-derived xenograft (PDX) models. AraC-treated AML cells are not consistently enriched for either immature cells or quiescent cells. AraC treatment does not enrich for LICs as measured by limiting dilution in secondary transplantations. Rather chemotherapy resistant cells in vivo have high levels of reactive oxygen species (ROS) and a gene signature consistent with oxidative phosphorylation (OXPHOS). Treatment of human HIGH OXPHOS but not LOW OXPHOS AML cell lines showed chemotherapy resistance in vivo, showing that essential mitochondrial functions make significant contributions to AraC resistance in AML. Accordingly, targeting mitochondrial OXPHOS metabolism through the inhibition of mitochondrial protein synthesis, the electron transfer chain or fatty acid oxidation induced an energetic shift towards LOW OXPHOS and strongly enhanced anti-leukemic effects of AraC in AML cells. These results demonstrate that chemotherapy resistance in AML is not necessarily associated with stemness but is highly dependent on a distinct oxidative metabolism, and that the HIGH OXPHOS gene signature is a robust hallmark of the AraC response in PDX and a promising therapeutic avenue to treat AML residual disease.
Chemotherapy-Resistant Human Acute Myeloid Leukemia Cells Are Not Enriched for Leukemic Stem Cells but Require Oxidative Metabolism.
Specimen part, Disease, Treatment, Subject
View SamplesThe size and scope of microarray experiments continue to increase. However, datasets generated on different platforms or at different centres contain biases. Improved techniques are needed to remove platform- and batch-specific biases. One experimental control is the replicate hybridization of a subset of samples at each site or on each platform to learn the relationship between the two platforms. To date, no algorithm exists to specifically use this type of control. LTR is a linear-modelling-based algorithm that learns the relationship between different microarray batches from replicate hybridizations. LTR was tested on a new benchmark dataset of 20 samples hybridized to different Affymetrix microarray platforms. Before LTR, the two platforms were significantly different; application of LTR removed this bias. LTR was tested with six separate data pre-processing algorithms, and its effectiveness was independent of the pre-processing algorithm. Sample-size experiments indicate that just three replicate hybridizations can significantly reduce bias. An R library implementing LTR is available.
LTR: Linear Cross-Platform Integration of Microarray Data.
Sex
View Samplesaffy_rice_2011_03 - affy_compartimentation_rice_albumen_embryon - During germination, the rice seed goes from a dry quiescent state to an active metabolism. As with all cereals, the rice seed is highly differentiated between the embryo (that will give rise to the future plantlet) and the endosperm (that contains the seed storage compounds and that will degenerate). The molecular mechanisms operating in the rice seed embryo have begun to be described. Yet, very few studies have focused specifically on the endosperm during the germination process. In particular, the endosperm is mostly addressed with regards to its storage proteins but we have detected a large protein diversity by two-dimensional electrophoresis. Similarly, the endosperm is rich in total RNA which suggest that gene expression coming from seed maturation could play a role during the germination process. In this context, we want to compare the transcriptome of the embryo and the endosperm during rice seed germination. -We germinate rice seeds of the first sequenced rice cultivar i.e. Nipponbare during 0, 4, 8, 12, 16 and 24h of imbibition in sterile distilled water. Germination occurs under constant air bubbling, in the dark at 30C. These rice seeds are then manually dissected into embryo and endosperm fractions. -The embryo-derived samples are abbreviated in E while the endosperm samples are abbreviated A. The germination time-point is indicated after the letter (e.g. E8 for embryo samples harvested after 8 hours of germination). Finally, the biological repetition number is indicated before the letter and the time digit (e.g. 1-E8 for an embryo sample from the first repetition at 8 hours of imbibition).
Compartmentation and dynamics of flavone metabolism in dry and germinated rice seeds.
Specimen part
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