We recently identified ISRIB as a potent inhibitor of the integrated stress response (ISR). ISRIB renders cells resistant to the effects of eIF2a phosphorylation and enhances long-term memory in rodents (10.7554/eLife.00498). Here we show by genome-wide in vivo ribosome profiling that translation of a restricted subset of mRNAs is induced upon ISR activation. ISRIB substantially reversed the translational effects elicited by phosphorylation of eIF2a and induced no major changes in translation or mRNA levels in unstressed cells. eIF2a phosphorylation-induced stress granule (SG) formation was blocked by ISRIB. Strikingly, ISRIB addition to stressed cells with pre-formed SGs induced their rapid disassembly, liberating mRNAs into the actively translating pool. Restoration of mRNA translation and modulation of SG dynamics may be an effective treatment of neurodegenerative diseases characterized by eIF2a phosphorylation, SG formation and cognitive loss. Overall design: Ribosome profiling with paired RNA-seq
The small molecule ISRIB reverses the effects of eIF2α phosphorylation on translation and stress granule assembly.
No sample metadata fields
View SamplesMicroRNAs (miRNAs) are endogenous ~22-nucleotide RNAs that mediate important gene-regulatory events by pairing to the mRNAs of protein-coding genes to direct their repression. Repression of these regulatory targets leads to decreased translational efficiency and/or decreased mRNA levels, but the relative contributions of these two outcomes have been largely unknown, particularly for endogenous targets expressed at low-to-moderate levels. Here, we use ribosome profiling to measure the overall effects on protein production and compare these to simultaneously measured effects on mRNA levels. For both ectopic and endogenous miRNA regulatory interactions, lowered mRNA levels account for most (=84%) of the decreased protein production. These results show that changes in mRNA levels closely reflect the impact of miRNAs on gene expression and indicate that destabilization of target mRNAs is the predominant reason for reduced protein output. Overall design: Examine ribosome footprints and mRNA abundance of HeLa cells transfected with miR-1 or miR-155, versus mock-transfected cells, at two different time points post-transfection. Supplementary processed data files linked below. mir155_summaryTable.txt: log2 fold changes (miR-155-transfected versus mock-transfected HeLa cells, 32hr). mir1_summaryTable.txt: log2 fold changes (miR-1-transfected versus mock-transfected HeLa cells, 32hr).
Mammalian microRNAs predominantly act to decrease target mRNA levels.
No sample metadata fields
View SamplesMicroRNAs (miRNAs) are endogenous ~22-nucleotide RNAs that mediate important gene-regulatory events by pairing to the mRNAs of protein-coding genes to direct their repression. Repression of these regulatory targets leads to decreased translational efficiency and/or decreased mRNA levels, but the relative contributions of these two outcomes have been largely unknown, particularly for endogenous targets expressed at low-to-moderate levels. Here, we use ribosome profiling to measure the overall effects on protein production and compare these to simultaneously measured effects on mRNA levels. For both ectopic and endogenous miRNA regulatory interactions, lowered mRNA levels account for most (84%) of the decreased protein production. These results show that changes in mRNA levels closely reflect the impact of miRNAs on gene expression and indicate that destabilization of target mRNAs is the predominant reason for reduced protein output.
Mammalian microRNAs predominantly act to decrease target mRNA levels.
Time
View SamplesMicroRNAs (miRNAs) are endogenous ~22-nucleotide RNAs that mediate important gene-regulatory events by pairing to the mRNAs of protein-coding genes to direct their repression. Repression of these regulatory targets leads to decreased translational efficiency and/or decreased mRNA levels, but the relative contributions of these two outcomes have been largely unknown, particularly for endogenous targets expressed at low-to-moderate levels. Here, we use ribosome profiling to measure the overall effects on protein production and compare these to simultaneously measured effects on mRNA levels. For both ectopic and endogenous miRNA regulatory interactions, lowered mRNA levels account for most (84%) of the decreased protein production. These results show that changes in mRNA levels closely reflect the impact of miRNAs on gene expression and indicate that destabilization of target mRNAs is the predominant reason for reduced protein output.
Mammalian microRNAs predominantly act to decrease target mRNA levels.
Time
View SamplesThe ability to sequence genomes has far outstripped approaches for deciphering the information they encode. Here we present a suite of techniques, based on ribosome profiling (the deep-sequencing of ribosome-protected mRNA fragments), to provide genome-wide maps of protein synthesis as well as a pulse-chase strategy for determining rates of translation elongation. We exploit the propensity of harringtonine to cause ribosomes to accumulate at sites of translation initiation together with a machine learning algorithm to define protein products systematically. Analysis of translation in mouse embryonic stem cells reveals thousands of strong pause sites and novel translation products. These include amino-terminal extensions and truncations and upstream open reading frames with regulatory potential, initiated at both AUG and non-AUG codons, whose translation changes after differentiation. We also define a new class of short, polycistronic ribosome-associated coding RNAs (sprcRNAs) that encode small proteins. Our studies reveal an unanticipated complexity to mammalian proteomes. Overall design: Examination of translation in mouse embryonic stem cells and during differentiation into embryoid bodies
Ribosome profiling provides evidence that large noncoding RNAs do not encode proteins.
Cell line, Treatment, Subject
View SamplesMeiosis 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. Overall design: Fine mapping of gene expression through meiosis reveals extensive regulation of protein synthesis and widespread non-canonical translation.
High-resolution view of the yeast meiotic program revealed by ribosome profiling.
Cell line, Subject
View SamplesMetazoan development depends on accurate execution of differentiation programs that allow pluripotent stem cells to adopt specific fates. Differentiation is brought about by global changes to chromatin architecture and transcriptional networks, yet whether other regulatory events support cell fate determination is less well understood. Using a human embryonic stem cell model, we identified the vertebrate-specific ubiquitin ligase Cul3KBTBD8 as an essential regulator of neural crest cell formation. Cul3KBTBD8 monoubiquitylates NOLC1 and its paralog TCOF1, whose mutation underlies the developmental disease Treacher Collins Syndrome that is characterized by a loss of cranial neural crest cells. Ubiquitylation of NOLC1 and TCOF1 drives formation of a platform that connects RNA polymerase I with ribosome modification enzymes, thereby altering the translational program of differentiating cells to support the generation of neural crest cells. We conclude that the dynamic regulation of ribosome function is an important feature of cell fate determination.
Cell-fate determination by ubiquitin-dependent regulation of translation.
Cell line
View SamplesAging is associated with the decline of protein, cell, and organ function. Here, we use an integrated approach to characterize gene expression, bulk translation, and cell biology in the brains and livers of young and old rats. We identify 468 differences in protein abundance between young and old animals. The majority are a consequence of altered translation output, that is, the combined effect of changes in transcript abundance and translation efficiency. In addition, we identify 130 proteins whose overall abundance remains unchanged but whose sub-cellular localization, phosphorylation state, or splice-form varies. While some protein-level differences appear to be a generic property of the rats' chronological age, the majority are specific to one organ. These may be a consequence of the organ's physiology or the chronological age of the cells within the tissue. Taken together, our study provides an initial view of the proteome at the molecular, sub-cellular, and organ level in young and old rats. Overall design: RNA-Seq and ribosome profiling from matched young and old rat liver and brain
Integrated Transcriptome and Proteome Analyses Reveal Organ-Specific Proteome Deterioration in Old Rats.
No sample metadata fields
View SamplesPiwi-interacting small RNAs (piRNAs) of fetal prospermatogonia of mice have been strongly implicated in transposon control. In contrast, little is known about biogenesis and function of abundant piRNAs from adult testes expressed in late spermatocytes and round spermatids. These so-called "pachytene" piRNAs are processed from long non-coding piRNA precursors and have no defined RNA targets in the transcriptome even though their binding partner Piwi, MIWI, is essential for spermiogenesis and fertility. Here we report that 129SvJae mice lacking Maelstrom (MAEL), a conserved piRNA pathway protein, exhibit spermiogenic arrest with defects in acrosome and flagellum formation. Further analysis revealed MAEL association with RNPs containing MIWI, TDRD6, and processed intermediates of pachytene piRNA precursors of various length. Loss of MAEL causes a 10-fold drop in pachytene piRNA levels but an increase in piRNAs from abundantly expressed mRNAs. These results suggest a MAEL-dependent mechanism for the selective processing of pachytene piRNA precursor into piRNAs. Strikingly, ribosome profiling of Mael-null testes revealed that reduced piRNA production is accompanied by reduced translation of over 800 spermiogenic mRNAs including those encoding acrosome and flagellum proteins. In light of recent reports of piRNA-independent protection of translationally repressed mRNPs by MIWI and piRNA-dependent turnover of MIWI, we propose that pachytene piRNAs function by controlling the availably of MIWI for the translational repression of spermiogenic mRNAs. Overall design: piRNA sequencing, RNA immunoprecipitation, and expression measurements (RNA-Seq and ribosome profiling) in wild-type and Mael -/- testes
Reduced pachytene piRNAs and translation underlie spermiogenic arrest in Maelstrom mutant mice.
Specimen part, Cell line, Subject
View SamplesWe report that AUF1 modulates global mRNA stability and translation, in turn promoting the maintenance of DNA integrity. Overall design: Please see individual series. For AUF1 PAR-CLIP, the four isoforms of AUF1 (p37, p40, p42, and p45) tagged with a Flag epitope were expressed in HEK293 cells. For total RNA-Seq HEK293 cells were transfected with Control siRNA, AUF1 siRNA, Empty Vector, Flag-AUF1 p37, p40, p42, or p45 as well as WI-38 cells were collected at PDL 15 and 55 and also transfected with Control siRNA, AUF1 siRNA, HuR siRNA. For Ribo-Seq HeLa cells were transfected with Control siRNA, AUF1 siRNA, or HuR siRNA.
PAR-CLIP analysis uncovers AUF1 impact on target RNA fate and genome integrity.
No sample metadata fields
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