The discovery of the small regulatory RNA populations has changed our vision of cellular regulations. Indeed, loaded on Argonaute proteins they formed ribonucleoprotein complexes that target complementary sequences and achieved widespread silencing mechanisms conserved in most eukaryotes. The recent development of deep sequencing approaches highly contributed to their detection. Small RNA isolation form cells and/or tissues remains a crucial stage to generate robust and relevant sequencing data. In 2006, a novel strategy based on anion-exchange chromatography has been purposed as an alternative to the standard size-isolation purification procedure. However, the eventual biases of such a method have been poorly investigated. Moreover, this strategy not only relies on advanced technical skills and expensive material but is time consuming and requires an elevated starting biological material amount. Using bioinformatic comparative analysis of six independent small RNA-sequencing libraries of Drosophila ovaries, we here demonstrate that anion-exchange chromatography purification prior to small RNA extraction unbiasedly enriches datasets in bona fide reads (small regulatory RNA reads) and depletes endogenous contaminants (ribosomal RNAs and degradation products). The resulting increase of sequencing depth provides a major benefit to study rare populations. We then developed a fast and basic manual procedure to purify loaded small non coding RNAs using anion-exchange chromatography at the bench. We validated the efficiency of this new method and used this strategy to purify small RNAs from various tissues and organisms. We moreover determined that our manual purification increases the output of the previously described anion-exchange chromatography procedure. Overall design: Comparison of small regulatory RNA populations obtained after three different small RNA purification procedures
A user-friendly chromatographic method to purify small regulatory RNAs.
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The maintenance of genome integrity is an essential trait to the successful transmission of genetic information. In animal germ cells, piRNAs guide PIWI proteins to silence transposable elements (TEs) in order to maintain genome integrity. In insects, most of TE silencing in the germline is achieved by secondary piRNAs that are produced by a feed-forward loop (the ping-pong cycle), which requires the piRNA-directed cleavages of two types of RNAs: mRNAs of functional euchromatic TEs and heterochromatic transcripts that contain defective TE sequences. The first cleavage which initiates such amplification loop remains poorly understood. Taking advantage of the existence of strains that are devoid of functional copies of the LINE-like I-element, we report that in such Drosophila ovaries, the initiation of a ping-pong cycle is achieved only by secondary I-element piRNAs that are produced in the ovary and deposited in the embryonic germline. This unusual secondary piRNA biogenesis, detected in the absence of functional I-element copies, results from the processing of sense and antisense transcripts of several different defective I-elements. Once acquired, for instance after ancestor aging, this capacity to produce heterochromatic-only secondary piRNAs is partially transmitted through generations via maternal piRNAs. Furthermore, such piRNAs acting as ping-pong initiators in a chromatin-independent manner confer to the progeny a high capacity to repress the I-element mobility. Our study explains at the molecular level the basis for epigenetic memory of maternal immunity that protects females from hybrid dysgenesis caused by transposition of paternally inherited functional I-elements. Overall design: Comparison of Drosophila small RNA populations in ovaries and/or eggs from 3-day-old or 25-day-old females.
piRNA-mediated transgenerational inheritance of an acquired trait.
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Transcriptomic comparison of FVB mouse strain lung Cells one week upon injecting mice intraperitoneally with either saline or Urethane. Mouse lung cell were also compared at the transcriptomic level with the mouse lung adenocarcinoma cell line FULA 1, which was established in our lab
IκB Kinase α Is Required for Development and Progression of <i>KRAS</i>-Mutant Lung Adenocarcinoma.
Specimen part, Cell line, TreatmentView Samples
We compared different mouse cancer cell lines to identify their unique cell signatures.
<i>NRAS</i> destines tumor cells to the lungs.
Specimen part, Cell lineView Samples
The cAMP responsive element binding protein (CREB) pathway has been involved in two major cascades of gene expression regulating neuronal function. The first one presents CREB as a critical component of the molecular switch that control longlasting forms of neuronal plasticity and learning. The second one relates CREB to neuronal survival and protection. To investigate the role of CREB-dependent gene expression in neuronal plasticity and survival in vivo, we generated bitransgenic mice expressing A-CREB, an artificial peptide with strong and broad inhibitory effect on the CREB family, in forebrain neurons in a regulatable manner. The expression of ACREB in hippocampal neurons impaired L-LTP, reduced intrinsic excitability and the susceptibility to induced seizures, and altered both basal and activity-driven gene expression. In the long-term, the chronic inhibition of CREB function caused severe loss of neurons in the CA1 subfield as well as in other brain regions. Our experiments confirmed previous findings in CREB deficient mutants and revealed new aspects of CREB-dependent gene expression in the hippocampus supporting a dual role for CREB-dependent gene expression regulating intrinsic and synaptic plasticity and promoting neuronal survival. manufacturer's protocol.
Inhibition of cAMP response element-binding protein reduces neuronal excitability and plasticity, and triggers neurodegeneration.
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Wild type Columbia and serrate-1 globular stage embryos were sequenced in order to profile miRNAs which are expressed in embryogenesis in Arabidopsis thaliana Overall design: Two biological replicates, two conditions
Arabidopsis thaliana miRNAs promote embryo pattern formation beginning in the zygote.
Specimen part, SubjectView Samples
Differential gene expression profiling was performed in two lymphoblastoid cell lines with different radiosentivitity, one radiosensitive (RS) and another radioresistant (RR), after different post-irradiation times. A greater and a prolonged transcriptional response after irradiation was induced in the RS cell line. Functional analysis showed that 24 h after irradiation genes involved in DNA damage response, negative regulation of the cell cycle and apoptosis were still differentially up-regulated in the RS cell line but not in the RR cell line. Overall design: Sham-irradiated and irradiated (2 Gy) cell cultures of the RS and the RR cell line were incubated at 37ÂºC for 4 and 24 h and 14 days. After that, RNA was extracted and sequenced with QuantSeq technology
Differences in DNA Repair Capacity, Cell Death and Transcriptional Response after Irradiation between a Radiosensitive and a Radioresistant Cell Line.
Specimen part, Cell line, Treatment, Subject, TimeView Samples
Strain differences in gene expression in the hypothalamus of BXD recombinant inbred mice
Sex-specific modulation of gene expression networks in murine hypothalamus.
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We used an inducible shRNA system and RNA-Seq to examine gene expression changes in acute myeloid leukemia THP1 cells following silencing of RUVBL2. RUVBL2 is a AAA+ ATPase that functions in a number of cellular processes, including chromatin remodeling and transcriptional control, and is critical for survival of acute myeloid leukemia cells and in vivo disease progression. Overall design: Total cellular RNA was extracted using the RNeasy Plus Mini Kit from THP1 cells transduced with RUVBL2-specific inducible shRNA, following 2 and 4 days exposure to doxycycline or medium controls. In total, 6 pairs of control and doxycycline-treated samples were analysed (3 control and 3 doxycycline-treated for each time-point).
The AAA+ATPase RUVBL2 is essential for the oncogenic function of c-MYB in acute myeloid leukemia.
Specimen part, Cell line, Subject, TimeView Samples
Approximately 2.5 mg dry Col-0 seedlings were surface sterilized and stratified for 2 days at 4degreesC in liquid media containing 1.5% sucrose (w/v) before being transferred to light with constant shaking at 100 rpm on an orbital shaker. After 7 days, the seedling clusters were subjected to the treatments for 1 hr followed by total RNA isolation using the RNAqueous kit (Ambion). Each treatment was performed in triplicate or quadruplicate. All labeling (Enzo) and hybridization (Affymetrix) procedures were performed as directed by the manufacturers. Raw probe intensities output by the Affymetrix MAS software were processed using the RMA algorithm to obtain an expression measure for each gene on each array.
Identification of inhibitors of auxin transcriptional activation by means of chemical genetics in Arabidopsis.
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