Unknown,Transcriptomics,Genomics,Proteomics

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Distinct inhibitory effects on mTOR signaling by ethanol and INK128 in diffuse large B-cell lymphoma

ABSTRACT: The mechanistic target of rapamycin, (mTOR) kinase plays a pivotal role in controlling critical cellular growth and survival pathways, and its aberrant induction is implicated in cancer pathogenesis. Therefore, suppression of active mTOR signaling has been of great interest to researchers; several mTOR inhibitors have been discovered to date. Ethanol (EtOH), similar to pharmacologic mTOR inhibitors, has been shown to suppress the mTOR signaling pathway, though in a non-catalytic manner. Despite population studies showing that the consumption of EtOH has a protective effect against hematological malignancies, the mechanisms behind EtOHM-bM-^@M-^Ys modulation of mTOR activity in cells and its downstream consequences are largely unknown. Here we evaluated the effects of EtOH on the mTOR pathway, in comparison to the active-site mTOR inhibitor INK128, and compared translatome analysis of their downstream effects in diffuse large B-cell lymphoma (DLBCL). SUDHL-2 and SUDHL-4 diffuse large B-cell lymphoma (DLBCL) cell lines (ATCC) were cultured in RPMI Medium 1640 (Gibco BRL) supplemented with 10% fetal bovine serum (FBS) at 37M-BM-0C in 5% CO2. EtOH-treated cells were cultured in sealed flasks to maintain EtOH concentrations, 20mM in the culture medium, water was added to EtOH control wells. INK128-treated cells were treated with INK128 at 40nM (Selleckchem) dissolved in dimethyl sulfoxide (DMSO) or 0.01% DMSO was added for the control wells. To create polysomal fractions, cells were lysed in cytoplasmic lysis buffer (5mM Tris, 2.5mM MgCl2, 1.5mM KCl, 1% Triton X-100, 0.5% Sodium Deoxycholate and 2 mM DTT), loaded on 10 - 50% linear sucrose gradients and fractionated. The RNA in each fraction was monitored by optical density measurement (A254) and eleven fractions were collected with a fraction collector (Brandel). The RNA from each fraction was isolated by Trizol (Invitrogen) and used for RT-qPCR analysis. RNA from high molecular weight polysomal fractions, with actively translated mRNAs (fractions 9 - 11) were pooled and used for microarray analysis. RNA was isolated using Qiagen RNeasy protocols and quality and quantity were checked with an Agilent 2100 Bio-Analyzer using RNA 6000 Nano chips. Labeling and amplification were done with the standard Illumina protocol and the biotin-labeled cRNA was hybridized to Illumina's HumanHT-12 V4.0 Expression BeadChip. The arrays were washed, blocked and the biotin-labeled cRNA was detected by staining with streptavidin-Cy3.

ORGANISM(S): Homo sapiens

SUBMITTER: Kevin Becker

PROVIDER: E-GEOD-62790 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Malaria is caused by Plasmodium parasites, which are transmitted via the bites of infected Anopheline mosquitoes. Midgut invasion is a major bottleneck for Plasmodium development inside the mosquito vectors as a rapidly responding immune system recognizes ookinetes and recruits killing factors from the midgut and surrounding tissues, dramatically reducing the population of invading ookinetes before they can successfully traverse the midgut epithelium. Understanding molecular details of the parasite-vector interactions requires precise measurement of nascent protein synthesis in the mosquito during Plasmodium infection. Current expression profiling primarily monitors alterations in steady-state levels of mRNA, but does not address the equally critical issue of whether the proteins encoded by the mRNAs are actually synthesized. In this study, we used sucrose density gradient centrifugation to isolate actively translating Anopheles gambiae mRNAs based upon their association with polyribosomes (polysomes). The proportion of individual gene transcripts associated with polysomes, which is determined by RNA deep sequencing, reflects mRNA translational status. This approach led to identification of 1017 mosquito transcripts that were primarily regulated at the translational level after ingestion of Plasmodium falciparum-infected blood. Caspar, a negative regulator of the NF-kappaB transcription factor Rel2, appears to be substantially activated at the translational levels during Plasmodium infection. In addition, transcripts of Dcr1, Dcr2 and Drosha, which are involved in small RNA biosynthesis, exhibited enhanced associations with polysomes after P. falciparum challenge. This observation suggests that mosquito microRNAs may play an important role in reactions against Plasmodium invasion. We analyzed both total cellular mRNAs and mRNAs that are associated with polysomes to simultaneously monitor transcriptomes and nascent protein synthesis in the mosquito. This approach provides more accurate information regarding the rate of protein synthesis, and identifies some mosquito factors that might have gone unrecognized because expression of these proteins is regulated mainly at the translational level rather than at the transcriptional level after mosquitoes ingest a Plasmodium-infected blood meal. Midguts from female Anopheles gambiae mosquitoes were dissected at around 24 h after ingestion of P. falciparum-infected blood. Mosquitoes fed on uninfected blood were used as control. A portion of the midguts were used for isolation of total cellular RNA. Extracts of the remaining midguts were fractionated over sucrose density gradients, and fifteen fractions were collected from the top of each gradient. Non-polysomal fractions, as well as polysomal fractions were combined, respectively, to obtain two RNA pools per gradient for three independent experiments. The first, last and the sample between non-polysomal and polysomal, were all discarded to ensure pure pools from each set. A fourth experiment was conducted where the polysomal and non-polysomal samples were not pooled, to be used later for qRT-PCR. The mRNA levels of individual mosquito genes in polysome (PS) fractions, nonpolysome (NP) fractions and unfractionated steady-state (total) RNA were determined using high throughput RNA deep sequencing. Each RNA pool generated 2.1-9.8 million raw read . Signal intensities of transcripts from each PS pool were compared to those of transcripts from a matching NP pool. To quantify the translational status of individual mRNA species, we define the relative PS loading [PL=P/(P+NP)] as the extent of mRNA association with polysomes. PL values were compared between the mosquitoes fed on P. falciparum-infected or -uninfected blood.

Project description:High activation of the PI3K-AKT-mTOR pathway is characteristic for T-cell acute lymphoblastic leukemia (T-ALL). Here we investigated how 4EGI-1, a small inhibitor of cap-dependent translation, induces apoptosis in T-ALL clones displaying hyperactive PI3K-AKT-mTOR signaling. 4EGI-1 treatment reduced the ribosomal occupancy of transcripts that define the molecular difference between T-ALL blasts and normal thymocytes. These transcripts encoded proteins for the translational machinery, for mitochondrial metabolism as well as oncoproteins such as Cyclin D1, Bcl-2 and c-myc. Therefore, targeting translation initiation proves valuable in situations where mTOR is activated by multiple events. For each biological replicate 5 x 107 #483 T-ALL cells were treated with 100 M-NM-<M 4EGI-1 or DMSO. After 2 h incubation at 37M-BM-0C cells were washed in ice-cold PBS containing cycloheximide (0.1 mg/ml), pelleted and resuspended in extraction buffer (20 mM Tris-HCl, pH 8.0, 140 mM KCl, 0.5 mM DTT, 5 mM MgCl2, 0.5 % nonidet-P40, 0.1 mg/ml cycloheximide, 10000 IU/ml dalteparin sodium) and incubated for 5 min on ice. All subsequent steps were carried out in the cold. After centrifugation for 10 min at 12000 x g, 0.4 ml supernatant was layered onto a 12 ml linear sucrose gradient (10 M-bM-^@M-^S 50% sucrose [w/v] in extraction buffer without nonidet-P40) and centrifuged at 4 M-BM-0C in an SW40Ti rotor (Beckman) at 35000 rpm without brake for 120 min. The gradients were harvested and absorbance profiles at 254 nm recorded (type 11 optical unit/UA-6 detector, ISCO). 1 ml fractions were collected and supplied with 0.1 volume of 3 M sodium acetate (pH 5.2) and 1 volume of isopropanol for overnight precipitation at -20 M-BM-0C. RNA was purified using Nucleospin RNAII tubes (Macherey & Nagel) following the manufacturerM-BM-4s protocol. For microarray analysis RNA from polysome fractions were pooled, precipitated by adding LiCl to a final concentration of 2 M and resolubilized in 15 M-BM-5l of RNase-free water. RNA concentrations were determined and the samples were stored at -80 M-BM-0C. The cytosolic/total- RNA sample for normalization was obtained from the same samples (106 treated/non-treated cells) using the standard Trizol protocol.

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Distinct inhibitory effects on mTOR signaling by ethanol and INK128 in diffuse large B-cell lymphoma

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