Ribosome profiling of wild-type and loc1- cells in S. cerevisiae
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ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae
SUBMITTER: Suzanne Komili
PROVIDER: E-GEOD-34438 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:Meiosis is a complex developmental process that generates haploid cells from diploid progenitors. We measured mRNA abundance and protein production through yeast sporulation and found strong temporal control for most genes, achieved through both mRNA levels and translational regulation. Monitoring the timing of protein production revealed novel factors involved in recombination and helped to illuminate the molecular basis of the broad restructuring of meiotic cells. We also found a strong increase in noncanonical translation at short open reading frames (sORFs) on unannnotated transcripts and upstream regions of known transcripts (uORFs). Ribosome occupancy at near-cognate uORFs was associated with more efficient ORF translation; while some AUG uORFs, often on regulated leader extensions, acted comptetitively. This work reveals a pervasive role for meiotic translational control and great complexity in genomic coding. Fine mapping of gene expression through meiosis reveals extensive regulation of protein synthesis and widespread non-canonical translation.
2012-01-06 | E-GEOD-34082 | biostudies-arrayexpress
Project description:In the process of translation, ribosomes first bind to mRNAs (translation initiation) and then move along the mRNA (elongation) to synthesize proteins. Elongation pausing is deemed highly relevant to co-translational folding of nascent peptides and the functionality of protein products, which positioned the evaluation of elongation speed as one of the central questions in the field of translational control. By employing three types of RNA-seq methods, we experimentally and computationally resolved elongation speed at individual gene level and under physiological condition in human cells. We proposed the elongation velocity index (EVI) as a relative measure and successfully distinguished slow-translating genes from the background translatome. The proteins encoded by the low-EVI genes are more stable than the proteome background. In normal cell and lung cancer cell comparisons, we found that the relatively slow-translating genes are relevant to the maintenance of malignant phenotypes. In addition, we identified cell-specific slow-translating codons, which may serve as a causal factor of elongation deceleration. We sequenced mRNA, translating mRNA (RNC-mRNA) and ribosome footprints in normally growing HeLa cells.
2016-02-09 | E-GEOD-46613 | biostudies-arrayexpress
Project description:DEAD-box RNA helicases eIF4A and Ded1 are believed to promote translation initiation by resolving mRNA secondary structures that impede ribosome attachment at the mRNA 5’ end or subsequent scanning of the 5’UTR, but whether they perform distinct functions or act redundantly in vivo is poorly understood. We compared the effects of mutations in Ded1 or eIF4A on global translational efficiencies (TEs) in yeast by ribosome footprint profiling. Despite similar reductions in bulk translation, inactivation of a cold-sensitive Ded1 mutant substantially reduced the TEs of >600 mRNAs, whereas inactivation of a temperature-sensitive eIF4A mutant yielded <40 similarly impaired mRNAs. The broader requirement for Ded1 did not reflect more pervasive secondary structures at low temperature, as inactivation of temperature-sensitive and cold-sensitive ded1 mutants gave highly correlated results. Interestingly, Ded1-dependent mRNAs exhibit greater than average 5’UTR length and propensity for secondary structure, implicating Ded1 in scanning though structured 5' UTRs. Reporter assays confirmed that cap- distal stem-loop insertions increase dependence on Ded1 but not eIF4A for efficient translation. While only a small fraction of mRNAs is strongly dependent on eIF4A, this dependence is significantly correlated with requirements for Ded1 and 5’UTR features characteristic of Ded1- dependent mRNAs. Our findings suggest that Ded1 is critically required to promote scanning through secondary structures within 5’UTRs; and while eIF4A cooperates with Ded1 in this function, it also promotes a step of initiation common to virtually all yeast mRNAs. We compared the effects of mutations in Ded1 or eIF4A on global translational efficiencies (TEs) in yeast by ribosome footprint profiling.The study includes 32 samples, comprised of 16 mRNA-Seq samples and 16 ribosome footprint profiling samples, derived from biological replicates of 3 mutant strains, ded1-cs, ded1-ts and tif1-ts, and the corresponding wild-type strains. The tif1-ts mutant and its wild-type counterpart were analyzed at 30°C and 37°C.
2015-03-02 | E-GEOD-66411 | biostudies-arrayexpress
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2012-08-08 | E-GEOD-39561 | biostudies-arrayexpress
Project description:Prions are infectious proteins that can adopt a structural conformation different from that of the normal protein. This change of conformation is then propagated among other molecules of the same protein. Prions are associated with neurodegenerative diseases in mammals, but are also found in fungi (in the yeast Saccharomyces cerevisiae and the filamentous fungus Podospora anserina), in which they control heritable traits. They are widespread in wild yeast strains, suggesting a biologically important role. [PSI+] is one of the most widely studied yeast prions. It corresponds to an aggregated conformation of the translational release factor, eRF3, which suppresses nonsense codons. [PSI+] modifies cellular fitness, inducing various phenotypes, depending on the genetic background. However, the genes displaying [PSI+]-controlled expression remain largely unknown. We used the recently described ribosome profiling approach to identify genes displaying changes in expression in the presence of [PSI+]. This made it possible to determine the positions of all active ribosomes within the genome, in both [PSI+] and [PSI-] isogenic strains. Comparisons of the translatomes and transcriptomes of the two strains revealed that the primary effect of [PSI+] was to repress genes involved in the stress response. Thus, we provide the first description of the global translational effect of [PSI+] and a new genetic explanation of the phenotypic differences between [PSI-] and [PSI+] strains under stress conditions. Comparisons of the translatomes and transcriptomes of the two strains. Comparisons of the translatomes of the two strainsM-BM- : a [PSI+] strain (two replicates) and a [PSI+] overexpressing SUP35-Cter strain.
2014-07-18 | E-GEOD-41590 | biostudies-arrayexpress
Project description:Embryogenesis requires the timely and coordinated activation of developmental regulators. It has been suggested that the recently discovered class of histone demethylases (UTX and JMJD3) that specifically target the repressive H3K27me3 modification play an important role in the activation of M-bM-^@M-^\bivalentM-bM-^@M-^] genes in response to specific developmental cues. To determine the requirements for UTX in pluripotency and development, we have generated Utx null ES cells and mutant mice. The loss of UTX had a profound effect during embryogenesis. Utx null embryos had reduced somite counts, neural tube closure defects and heart malformation which presented between E9.5 and E13.5. Unexpectedly, homozygous mutant female embryos were more severely affected than hemizygous mutant male embryos. In fact, we observed the survival of a subset of UTX-deficient males which were smaller in size and had reduced life-span. Interestingly, these animals were fertile with normal spermatogenesis. Consistent with a mid-gestation lethality, UTX null male and female ES cells gave rise to all three germ layers in teratoma assays although sex-specific differences could be observed in the activation of developmental regulators in embryoid body assays. Lastly, ChIP-seq analysis revealed an increase in H3K27me3 in Utx null male ES cells. In summary, our data demonstrate sex-specific requirements for this X-linked gene while suggesting a role for UTY during development. Examination of H3K27me3 and H3K4me3 in UtxKO ES cells (V6.5 background) vs UtxFlx (V6.5 background) ES cells grown in LIF containing ES cell media or treated with retinoic acid without LIF.
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2011-03-07 | E-GEOD-26449 | biostudies-arrayexpress
Project description:In this work, we characterized the epigenomic integrity of 17 hiPSC lines derived from six different cell types with varied reprogramming efficiencies. We demonstrate that epigenetic aberrations are a general feature of the hiPSC state and are independent of the somatic cell source. Additionally, we determine that both shared and line-specific epigenetic aberrations in hiPSCs can directly translate into changes in gene expression in both the pluripotent and differentiated states. Examination of differential methylation between iPSC and ESCs through differentiated states. Examination of differential methylation between iPSC and somatic cell source and iPSC and ESCs.
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