Ribosome footprinting in the cytosol and endoplasmic reticulum
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE31539 | GEO | 2011/12/20
SECONDARY ACCESSION(S): PRJNA145711
REPOSITORIES: GEO
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Project description:In eukaryotic cells, the spatial regulation of protein expression is frequently conferred through the coupling of mRNA localization and the local control of translation. mRNA localization to the endoplasmic reticulum (ER) is a prominent example of such regulation and serves a ubiquitous role in segregating the synthesis of secretory and integral membrane proteins to the ER. Recent genomic and biochemical studies have now expanded this view to suggest a role for the ER in global protein synthesis. We have utilized cell fractionation and ribosome profiling to obtain a genomic survey of the subcellular organization of mRNA translation and report that ribosomal loading of mRNAs, a proxy for mRNA translation, is biased to the ER. Notably, ER-associated mRNAs encoding both cytosolic and topogenic signal-encoding proteins display similar ribosome loading densities, suggesting that ER-associated ribosomes serve a global role in mRNA translation. We propose that the partitioning of mRNAs and their translation between the cytosol and ER compartments may represent a novel mechanism for the post-transcriptional regulation of gene expression. HEK293 cells were fractionated between the cytosol and endoplasmic reticulum. Within each fraction, ribosome footprints were generated and sequenced. In parallel, total mRNA was sequenced.
2011-12-20 | E-GEOD-31539 | biostudies-arrayexpress
Project description:The unfolded protein response (UPR) couples cellular translation rates and gene expression to the protein folding status of the endoplasmic reticulum (ER). Upon activation, the UPR machinery elicits a general suppression of protein synthesis and activation of stress gene expression, which act coordinately to restore protein folding homeostasis. We report here that UPR activation promotes the release of signal sequence-encoding mRNAs from the ER to the cytosol as a mechanism to decrease protein influx into the ER. This release of mRNA begins rapidly, then gradually recovers with ongoing stress. Upon release into the cytosol, these mRNAs have divergent fates: some synthesize full-length proteins, while others are translationally inactive and retain nascent protein chains. Together, these findings identify the dynamic subcellular localization of mRNAs and translation as a regulatory feature of the cellular response to protein folding stress. Cells were treated with a timecourse of Thapsigargin or DTT, then fractionated and analyzed by mRNA-seq or ribosome profiling
2014-08-28 | E-GEOD-53743 | biostudies-arrayexpress
Project description:Local mRNA translation in axons is critical for the spatial and temporal regulation of the axonal proteome. A wide variety of mRNAs are localized and translated in axons, however how protein synthesis is regulated at specific subcellular sites in axons remains unclear. Here, we establish that the axonal endoplasmic reticulum (ER) supports axonal translation in developing neurons. Axonal ER tubule disruption impairs local translation and ribosome distribution. Using nanoscale resolution imaging, we find that ribosomes make frequent contacts with axonal ER tubules in a translation-dependent manner and are influenced by specific extrinsic cues. We identify P180/RRBP1 as an axonally distributed ribosome receptor that regulates local translation and binds to mRNAs enriched for axonal membrane proteins. Importantly, the impairment of axonal ER – ribosome interactions causes defects in axon morphology. Our results establish an important role for the axonal ER in dynamically localizing mRNA translation which is important for proper neuron development.
2024-04-29 | GSE262262 | GEO
Project description:The initiation of translation begins with formation of a ribosome-mRNA complex. In bacteria, the 30S ribosomal subunit is recruited to many mRNAs through both base pairing with the Shine Dalgarno (SD) sequence and RNA-binding by ribosomal protein bS1. Translation can initiate on mRNAs that are being transcribed, and RNA polymerase (RNAP) can promote recruitment of the pioneering 30S. Here we have examined ribosome recruitment to mRNAs using cryogenic electron microscopy (cryo-EM), single-molecule fluorescence co-localization, and whole-cell cross-linking mass spectrometry. Structures of 30S-mRNA complexes show that bS1 delivers the mRNA to the ribosome for SD duplex formation and initial 30S subunit activation. RNAP associates flexibly with the 30S platform during nascent mRNA delivery and accelerates their association in a bS1-dependent manner in vitro. Collectively, our data provide a mechanistic framework for how the SD duplex, ribosomal proteins and RNAP cooperate in 30S recruitment to mRNAs and thereby establish transcription-translation coupling.
2024-11-15 | PXD048229 | JPOST Repository
Project description:Local translation within excitatory and inhibitory neurons is known to be involved in neuronal development and synaptic plasticity. Despite the extensive dendritic and axonal arborizations of monoaminergic neurons, the subcellular localization of protein synthesis has not been well-characterized in these populations. Here, we investigated mRNA localization in midbrain dopaminergic (mDA) neurons, cells with enormous axonal and dendritic projections, both of which can release dopamine (DA). Using highly-sensitive sequencing and imaging approaches in mDA axons, we found no evidence for axonal mRNA localization or translation. In contrast, we found that mDA neuronal dendritic projections into the substantia nigra reticulata (SNr) contain ribosomes and mRNAs encoding the DA synthesis, release, and reuptake machinery. Surprisingly, we found dendritic localization of mRNAs encoding synaptic vesicular release proteins in mDA neurons. Our results are consistent with a role for local translation in the regulation of DA transmission from dendrites, but not striatal axons. Finally, we defined a molecular signature of sparse mDA neurons in the SNr, including enrichment of an ER calcium pump previously undescribed in mDA neurons.
2021-07-27 | GSE180913 | GEO
Project description:Protein synthesis belongs to the most energy consuming processes in the cell. Lowering oxygen tension below normal (hypoxia) causes a rapid inhibition of global mRNA translation due to the decreased availability of energy. Interestingly, subsets of mRNAs pursue active translation under such circumstances. In human fibrosarcoma cells (HT1080) exposed to prolonged hypoxia (36 h, 1% oxygen) we observed that transcripts are either increasingly or decreasingly associated with ribosomes localized at the endoplasmic reticulum (ER). In a global setting it turned out that only 31% of transcripts showing elevated total-RNA levels were also increasingly present at the ER in hypoxia. These genes, regulated by its expression as well as its ER-localization, belong to the gene ontology’s “hypoxia response”, “glycolysis” and “HIF-1 transcription factor network” supporting the view of active mRNA translation at the ER during hypoxia. Interestingly, a large group of RNAs was found to be unchanged at the expression level, but translocate to the ER in hypoxia. Among these are transcripts encoding translation factors and >180 ncRNAs. In summary, we provide evidence that protein synthesis is favoured at the ER and, thus, partitioning of the transcriptome between cytoplasmic and ER associated ribosomes mediates adaptation of gene expression in hypoxia. Human fibrosarcoma HT1080 cells were cultured for 36 h under control/atmospheric (21% O2, 5% CO2, 37 °C) or hypoxic (1% O2, 5% CO2, 37°C) conditions. Total RNA (representing expression level) and ER (endoplasmatic reticulum)-RNA (representing transcript localization at ER) was isolated for both conditions. Pooled RNA samples from 5 independent biological experiments were used for microarray analysis.
2015-04-01 | E-GEOD-49029 | biostudies-arrayexpress
Project description:The subcellular localization and translation of messenger RNA (mRNA) supports functional differentiation between cellular compartments. In neuronal dendrites, local translation of mRNA provides a rapid and specific mechanism for synaptic plasticity and memory formation, and might be involved in the pathophysiology of certain brain disorders. Despite the importance of dendritic mRNA translation, little is known about which mRNAs can be translated in dendrites in vivo and when their translation occurs. Here we collect ribosome-bound mRNA from the dendrites of CA1 pyramidal neurons in the adult mouse hippocampus. We find that dendritic mRNA rapidly associates with ribosomes following a novel experience consisting of a contextual fear conditioning trial. High throughput RNA sequencing followed by machine learning classification reveals an unexpected breadth of ribosome-bound dendritic mRNAs, including mRNAs expected to be entirely somatic. Our findings are in agreement with a mechanism of synaptic plasticity that engages the acute local translation of functionally diverse dendritic mRNAs. RNA-Seq of ribosome-bound mRNA immunoprecipitated from dendrites and soma of CA1 pyramidal neurons in the mouse hippocampus
2014-07-30 | E-GEOD-58343 | biostudies-arrayexpress
Project description:A universal feature of the response to stress and nutrient limitation is transcriptional upregulation of genes encoding proteins important for survival. Interestingly, under many of these conditions overall protein synthesis levels are reduced, thereby dampening the stress response at the level of protein expression. For example, during glucose starvation in yeast, translation is rapidly and reversibly repressed, yet transcription of many stress- and glucose-repressed genes is increased. Using ribosome profiling and microscopy, we found that this transcriptionally upregulated gene set consists of two classes: (1) one producing mRNAs that are preferentially translated during glucose limitation and are diffusely localized in the cytoplasm – this class includes many heat shock protein mRNAs; and (2) another producing mRNAs that are poorly translated during glucose limitation, have high rates of translation initiation, and are concentrated in foci that co-localize with P bodies and stress granules – this class is enriched for glucose metabolism mRNAs. Remarkably, the information specifying differential localization and translation of these two classes of mRNAs is encoded in the promoter sequence – promoter responsiveness to heat shock factor (Hsf1) specifies diffuse cytoplasmic localization and preferential translation upon glucose starvation, whereas different promoter elements upstream of genes encoding poorly translated glucose metabolism mRNAs direct these mRNAs to RNA granules under glucose starvation. Thus, promoter sequences and transcription factor binding can influence not only mRNA levels, but also subcellular localization of mRNAs and the efficiency with which they are translated, enabling cells to tailor protein production to environmental conditions. Examination of mRNA translation in S. cerevisiae upon glucose starvation.
2014-07-28 | E-GEOD-56622 | biostudies-arrayexpress
Project description:Purpose: The goal of this study is to examine gene expression regulation at the transcriptional and translational levels in response to various forms of nutrient deprivation, and whether there are differences between isogenic transformed and non-transformed cells. Mehods: We apply high-throughput sequencing of ribosome footprints (ribosome profiling) and poly(A) RNA (RNA sequencing) in an isogenic pair of transformed (tamoxifen-treated) and non-transformed (ethanol control) MCF10A-ER-Src cells subjected to the metabolic stresses that differentially affect global protein synthesis (Figure 1): deprivation of glutamine (for 30min and 4 hours), glucose (4hours), cysteine/cystine (4hours) or leucine/isoleucine/valine (brach-chain aminoacids - BCAA) (4hours). The same experiments were also performed in transformed ER-Src MCF10A treated with torin1 (500nM) for 4 hours. Results: Genome-wide translational profiling of glutamine deprived ER-Src MCF10A cells (for 30 minutes) shows increased translation of uORFs-containing mRNAs and down-regulation of ribosomal protein mRNAs, which is followed by increased translation and transcription of cytokine and inflammatory mRNAs (after 4 hours of glutamine deprivation). The transcription and translation of inflammatory and cytokine mRNAs is also stimulated in response to 4 hours deprivation of glucose, cysteine/cystine and BCAA, with the extent of stimulation correlating with the i) decrease in global protein synthesis and ii) down-regulation of all translationally-repressed mRNAs or ribosomal protein mRNAs. Conclusions: Pro-inflammatory gene expression is associated with translational repression in response to short-term nutrient deprivation.
2018-07-01 | GSE114794 | GEO
Project description:Nascent peptide chain targeting to the endoplasmic reticulum (ER) membrane is required for correct localization and efficient translation of membrane-bound and secreted proteins. However, little is known about the contribution of RNA-binding proteins (RBPs) to the recognition, localization and translation of ER-localized mRNAs. In this work we used biochemical, transcriptomic and proteomic approaches to delineate the role of human HDLBP. PAR-CLIP analysis revealed that HDLBP directly and specifically interacted with more than 80% of all expressed ER-localized mRNAs. Interestingly, the binding to the coding sequence was most prominent for ER-localized mRNAs, while cytosolic mRNAs showed higher binding in the 3’UTR. HDLBP crosslinked strongly to long CU-rich motifs that resided more frequently in coding sequences of ER-localized but not in cytosolic mRNAs. This indicated that the primary sequence composition determines the basis for HDLBP binding specificity and its multivalent interactions with ER-bound mRNAs. PAR-CLIP analysis also revealed direct interactions of HDLBP with the RNA components of the translational apparatus, while in vivo proximity proteomics detected proteins involved in translation and components of the signal recognition particle (SRP). Functional studies using CRISPR-Cas9 HDLBP knockout cell lines in combination with ribosome profiling, pSILAC, and luciferase assays showed decreased translation efficiency of HDLBP target mRNAs, impaired protein synthesis and secretion in the knockout conditions. Finally, HDLBP absence resulted in decrease of lung tumor formation capacity in vivo. These results highlight a general function for HDLBP in the translation of ER -localized mRNAs via the secretory pathway and discover its relevance for cell profileration and tumor progression.
2022-06-09 | PXD018313 | Pride