Characterization of polysome enriched mRNAs following insulin treatment
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE61126 | GEO | 2015/10/01
SECONDARY ACCESSION(S): PRJNA260528
REPOSITORIES: GEO
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Project description:Liver samples were lysed (15 mM Tris-HCl (pH 8.0), 300 mM NaCl and 15 mM MgCl2, plus inhibitors (1 mg/ml heparin 100 µg/ml cycloheximide and 80 U RNAsin)), added to a 10-50% sucrose gradient and ultracentrifuged at 182,000x g for 2 hours. The gradient was aliquotted into 16 1ml fractions and added to Tri reagent (Sigma). RNA was extracted as per the manufacturer's instructions and then sub-pooled into fractions corresponding to monosomes, light polysomes, medium polysomes and heavy polysomes, according to ribosomal density (more ribosomal occupancy = higher translational activity = heavier, and therefore, located in the more dense fractions). Microarray analysis was performed by hybridising control (vehicle treated) monosomes against test (high-dose treated) monosomes on one microarray, control light polysomes against test light polysomes on a second microarray, and so forth for each sub-pool of fractions. Following microarray analysis there were a maximum of four values for each mRNA, corresponding to the proportional representation of that mRNA within each sub-pool of fractions. By calculating the change in values, i.e. degree of slope, across the monosomal region, the light polysomal region, the medium polysomal region and the dense polysomal region it was possible to determine any translational change in activity. In addition, the overall transcriptional change could be analysed for each mRNA.
2012-06-21 | GSE38807 | GEO
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.
2012-09-21 | E-GEOD-38707 | biostudies-arrayexpress
Project description:We use mRNA-seq in combination with polysome profiling to determine translational status for all mRNAs in Drosophila mature oocytes and activated eggs. Puromycin-treated lysates are used as a negative control in polysome profiling experiments. Additionally, we use ribosome footprinting to globally measure translational efficiency of mRNAs in wild type mature oocytes as well as wild type and png mutant activated eggs. Lysates of hand-dissected Drosophila mature oocytes (containing ~540 M-NM-<g of total RNA) were subjected to separation by velocity sedimentation through sucrose gradients. In this way, free mRNAs (present in RNPs fraction) or those comigrating with ribosomal subunits (40S or 60S+80S fractions) or with varying numbers of bound ribosomes (low polysomes (2-4 ribosomes), medium polysomes (5-9 ribosomes), and heavy polysomes (more than 10 ribosomes) can be separated based on their size and collected as sucrose gradient fractions. To compare quantitatively the levels of every mRNA across the polysome gradient fractions, we added 5ng of S. cerevisiae mRNA as an exogenous spike-in to each of the six fractions of interest: RNPs, 40S, 60S+80S, low polysomes, medium polysomes and heavy polysomes. RNA was extraced from these fractions, follwing proteinase K treatment, by hot acid phenol method. In case of unfractionated lysates, RNA was extracted using TRIzol (Invitrogen) according to manufacturerM-bM-^@M-^Ys instructions. mRNA-seq samples were prepared from 1 M-NM-<g of total RNA (in case of sucrose gradient fractions and unfractionated lysates) and subject to Illumina based sequencing. Puromycin-treated lysates of mature oocytes or 0-2h Drosophila activated eggs (containing ~540 M-NM-<g of total RNA) were also subjected to separation by velocity sedimentation through sucrose gradients. Puromycin causes premature termination of elongating ribosomes and thus it can be used to determine whether the mRNAs co-sedimenting with the polysomal peaks (defined here as M-bM-^IM-%5 ribosomes) were actively engaged in translation. As an independent approach to assess translation and obtain information on the position of ribosomes on mRNAs, we employed ribosome footprinting. In addition to analyzing the same samples, as by polysome profiling, we also analyzed png mutant activated eggs by ribosome footprinting. Ribosome footprint profiling measures the number of ribosome-protected fragments (RPFs) derived from the mRNAs of each gene, resulting in a singular value of translational efficiency (TE) for each gene (TE=RPF/RNA).
2014-06-12 | E-GEOD-52799 | biostudies-arrayexpress
Project description:Gametes rely heavily on post-transcriptional control mechanisms to regulate their differentiation. In eggs, the storage and selective temporal activation of maternal mRNAs is essential for normal development. In the male, transcription ceases during spermiogenesis necessitating the post-transcriptional regulation of many paternal mRNAs required for spermatid differentiation and spermatozoan function. Messenger RNAs that are being actively translated form polysomes. whereas translationally inactive mRNAs are often sequestered in ribonucleoproteins (RNPs). Here we combine polysome display and microarray analyses of RNP and polysome fractions of testes from prepuberal and adult mice to characterize the translation state of individual mRNAs as spermatogenesis proceeds.. Consistent with published reports, many post-meiotic mRNAs known to be translationally delayed shift from the RNPs into the polysomes, confirming the validity of this approach. In addition, based upon the criterion of movement from RNPs to polysomes, we detect another 742 mouse testicular genes showing dramatic shifts between RNPs and polysomes. One sub-group of 35 genes including the known translationally delayed Pgk2, are initially transcribed and translationally repressed in meiotic spermatocytes, and translated post-meiotically. This high-through-put approach defines the changing translation patterns of a large number of genes as male germ cells differentiate and identifies a new group of post-transcriptionally regulated meiotic transcripts for future study. Keywords: time course
2006-05-15 | GSE4711 | GEO
Project description:Liver samples were lysed (15 mM Tris-HCl (pH 8.0), 300 mM NaCl and 15 mM MgCl2, plus inhibitors (1 mg/ml heparin 100 µg/ml cycloheximide and 80 U RNAsin)), added to a 10-50% sucrose gradient and ultracentrifuged at 182,000x g for 2 hours. The gradient was aliquotted into 16 1ml fractions and added to Tri reagent (Sigma). RNA was extracted as per the manufacturer's instructions and then sub-pooled into fractions corresponding to monosomes, light polysomes, medium polysomes and heavy polysomes, according to ribosomal density (more ribosomal occupancy = higher translational activity = heavier, and therefore, located in the more dense fractions). Microarray analysis was performed by hybridising control (vehicle treated) monosomes against test (high-dose treated) monosomes on one microarray, control light polysomes against test light polysomes on a second microarray, and so forth for each sub-pool of fractions. Following microarray analysis there were a maximum of four values for each mRNA, corresponding to the proportional representation of that mRNA within each sub-pool of fractions. By calculating the change in values, i.e. degree of slope, across the monosomal region, the light polysomal region, the medium polysomal region and the dense polysomal region it was possible to determine any translational change in activity. In addition, the overall transcriptional change could be analysed for each mRNA. Dual colour microarrays performed on n = 3 samples, implementing a dye swap design. Control samples were treated with vehicle only. The treated samples had 1120mg/kg of the compound (Tetraethyl[(3-hydroxy-2-pyridyl)amino]-methanediphosphonate) for 15 days.
2012-06-20 | E-GEOD-38807 | biostudies-arrayexpress
Project description:Lysates from control or Trm6/61 overexpressing cells were fractionated on sucrose gradient to isolate polysomes. RNA extracted from heavy polysomal fractions was analyzed by microarray versus total RNA
2015-04-29 | E-MTAB-3537 | biostudies-arrayexpress
Project description:Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. mRNA species bound to membrane-associated polysomes were separated from other mRNAs by sedimentation equilibrium or sedimentation velocity. The distribution of individual transcripts in the 'membrane-bound' and 'cytosolic' fractions was quantitated for thousands of genes by hybridization to DNA microarrays. Transcripts known to encode secreted or membrane proteins were enriched in the membrane-bound fractions, whereas those known to encode cytoplasmic proteins were enriched in the fractions containing mRNAs associated with free and cytoplasmic ribosomes. On this basis, we identified over 275 human genes and 285 yeast genes that are likely to encode previously unrecognized secreted or membrane proteins. Keywords: Logical Set
2005-08-24 | GSE3180 | GEO
Project description:To identify mRNAs that are most translationally repressed following eIF4A inhibition and those that are relatively insensitive, polysome profiling was carried with and without eIF4A inhibition by hippuristanol treatment. Polysomal, sub-polysomal and total RNA was sequenced and we used a Bayesian model to identify mRNAs that with greatest confidence had shifted from the polysomal into the sub-polysomal fractions, from the sub-polysomal into the polysomal fractionsand those mRNAs that did not change in their polysomal to sub-polysomal ratio, following hipp treatment, which were termed eIF4A-dependent, eIF4A-antidependent and eIF4A-independent mRNAs respectively
2019-11-21 | GSE134888 | GEO
Project description:Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. mRNA species bound to membrane-associated polysomes were separated from other mRNAs by sedimentation equilibrium or sedimentation velocity. The distribution of individual transcripts in the 'membrane-bound' and 'cytosolic' fractions was quantitated for thousands of genes by hybridization to DNA microarrays. Transcripts known to encode secreted or membrane proteins were enriched in the membrane-bound fractions, whereas those known to encode cytoplasmic proteins were enriched in the fractions containing mRNAs associated with free and cytoplasmic ribosomes. On this basis, we identified over 275 human genes and 285 yeast genes that are likely to encode previously unrecognized secreted or membrane proteins. Computed
2005-08-24 | E-GEOD-3180 | biostudies-arrayexpress
Project description:Purpose: mRNA translation into protein is highly regulated, but the role of mRNA isoforms, noncoding RNAs (ncRNAs), and genetic variants has yet to be systematically studied. Using high-throughput sequencing (RNA-seq), we have measured cellular levels of mRNAs and ncRNAs, and their isoforms, in lymphoblast cell lines (LCL) and in polysomal fractions, the latter shown to yield strong correlations of mRNAs with expressed protein levels. Analysis of allelic RNA ratios at heterozygous SNPs served to reveal genetic factors in ribosomal loading. Methods: RNA-seq was performed on cytosolic extracts and polysomal fractions (3 ribosomes or more) from three lymphoblastoid cell lines. As each RNA fraction was amplified (NuGen kit), and relative contributions from various RNA classes differed between cytosol and polysomes, the fraction of any given RNA species loaded onto polysomes was difficult to quantitate. Therefore, we focused on relative recovery of the various RNA classes and rank order of single RNAs compared to total RNA. Results: RNA-seq of coding and non-coding RNAs (including microRNAs) in three LCLs revealed significant differences in polysomal loading of individual RNAs and isoforms, and between RNA classes. Moreover, correlated distribution between protein-coding and non-coding RNAs suggests possible interactions between them. Allele-selective RNA recruitment revealed strong genetic influence on polysomal loading for multiple RNAs. Allelic effects can be attributed to generation of different RNA isoforms before polysomal loading or to differential loading onto polysomes, the latter defining a direct genetic effect on translation. Several variants and genes identified by this approach are also associated with RNA expression and clinical phenotypes in various databases. Conclusions: These results provide a novel approach using complete transcriptome RNA-seq to study polysomal RNA recruitment and regulatory variants affecting protein translation.
2015-06-30 | GSE66135 | GEO