Introduction: A considerable proportion of mammalian gene expression undergoes circadian oscillations. Post-transcriptional mechanisms likely make important contributions to mRNA abundance rhythms. Aim: We have investigated how microRNAs contribute to core clock and clock-controlled gene expression using mice in which microRNA biogenesis can be inactivated in the liver. Results: While the hepatic core clock was surprisingly resilient to microRNA loss, whole transcriptome sequencing uncovered widespread effects on clock ouput gene expression. Cyclic transcription paired with microRNA-mediated regulation was thus identified as a widespread phenomenon that affected up to 30% of the rhythmic transcriptome and served to post-transcriptionally adjust the phases and amplitudes of rhythmic mRNA accumulation. However, only a few mRNA rhythms were actually generated by microRNAs. Finally, we pinpoint several microRNAs predicted to act as modulators of rhythmic transcripts, and identify rhythmic pathways particularly prone to microRNA regulation. Conclusion: Our study provides a comprehensive analysis of miRNA activity in shaping hepatic circadian gene expression and can serve as a valuable resource for further investigations into the regulatory roles that miRNAs play in liver gene expression and physiology. Overall design: RNA-Seq of rRNA-depleted total RNAs from two independent full time series around-the-clock of Dicer knockout and control mouse livers
MicroRNAs shape circadian hepatic gene expression on a transcriptome-wide scale.
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View SamplesBACKGROUND: The daily gene expression oscillations that underlie mammalian circadian rhythms show striking differences between tissues and involve post-transcriptional regulation. Both aspects remain poorly understood. We have used ribosome profiling to explore the contribution of translation efficiency to temporal gene expression in kidney, and contrasted our findings with liver data available from the same mice. RESULTS: Rhythmic translation of constantly abundant mRNAs affects largely nonoverlapping transcript sets with distinct phase clustering in the two organs. Moreover, tissue differences in translation efficiency modulate the timing and amount of protein biosynthesis from rhythmic mRNAs, consistent with organ-specificity in clock output gene repertoires and rhythmicity parameters. Our comprehensive datasets provided insights into translational control beyond temporal regulation. Between tissues, many transcripts show differences in translation efficiency, which are, however, of markedly smaller scale than mRNA abundance differences. Tissue-specific changes in translation efficiency are associated with specific transcript features and, intriguingly, globally counteracted and compensated transcript abundance variations, leading to higher similarity at the level of protein biosynthesis between both tissues. CONCLUSIONS: We show that tissue-specificity in rhythmic gene expression extends to the translatome and contributes to define the identities, the phases and the expression levels of rhythmic protein biosynthesis. Moreover, translational compensation of transcript abundance divergence leads to overall higher similarity at the level of protein production across organs. The unique resources provided through our study will serve to address fundamental questions of post-transcriptional control and differential gene expression in vivo. Overall design: A total of 48 mice were entrained under 12hours light:dark conditions for 2 weeks and also collected under 12hours light:dark. Mice were sacrificed every two hours during the 24 hours daily cycle. Two replicates per time point, each replicate is a pool of livers or kidneys from 2 animals.
Translational contributions to tissue specificity in rhythmic and constitutive gene expression.
Sex, Cell line, Subject, Time
View SamplesThrough post-transcriptional regulation of gene expression, miRNAs affect numerous regulatory pathways including those crucial for maintaining metabolic balance. Here we demonstrate that a neuronal-specific inhibition of miRNA maturation in adult mice leads to a rapid development of severe obesity, which is equally rapidly reversed. Development of obesity was associated with increased food intake and efficiency, and decreased locomotor activity. The ensuing decrease in body weight resembled a catabolic state with lowered O2-consumption and respiratory-exchange ratio. Brain transcriptome analyses in obese mice identified several obesity-related pathways including leptin, somatostatin, and nemo-like kinase signaling, as well as genes involved in feeding and appetite (e.g. Pmch, Neurotensin). A cluster of genes involved in synaptic plasticity was specifically enriched in post-obese mice that did not appear in obese mice. While other studies have identified a role for miRNAs in obesity our model is unique in that it allows for the study of processes involved in reversing obesity.
A neuron-specific deletion of the microRNA-processing enzyme DICER induces severe but transient obesity in mice.
Specimen part, Time
View SamplesDiurnal oscillations of gene expression are a hallmark of rhythmic physiology across most living organisms. Such oscillations are controlled by the interplay between the circadian clock and feeding rhythms. While rhythmic mRNA accumulation has been extensively studied, comparatively less is known about their transcription and translation. Here, we quantified simultaneously temporal transcription, accumulation, and translation of mouse liver mRNAs under physiological light-dark conditions and ad libitum or night-restricted feeding in wild-type and Bmal1 deficient animals. We found that rhythmic transcription predominantly drives rhythmic mRNA accumulation and translation for a majority of genes. Comparison of wild-type and Bmal1 KO mice shows that circadian clock and feeding rhythms have broad impact on rhythmic genes expression, Bmal1 deletion having surprisingly more impact at the post-transcriptional level. Translation efficiency is differentially regulated during the diurnal cycle for genes with 5'-TOP sequences and for genes involved in mitochondrial activity and harboring a TISU motif. The increased translation efficiency of 5'-TOP and TISU genes is mainly driven by feeding rhythms but Bmal1 deletion impacts also amplitude and phase of translation, including TISU genes. Together this study emphasizes the complex interconnections between circadian and feeding rhythms at several steps ultimately determining rhythmic gene expression and translation. Overall design: RNA-Seq from total RNA of mouse liver during the dirunal cycle. Time-series mRNA profiles of wild type (WT) and Bmal -/- mice under ad libitum and night restriced feeding regimen were generated by deep sequencing.
Diurnal Oscillations in Liver Mass and Cell Size Accompany Ribosome Assembly Cycles.
Cell line, Subject
View SamplesMammalian gene expression displays widespread circadian oscillations. Rhythmic transcription underlies the core clock mechanism, but it cannot explain numerous observations made at the level of protein rhythmicity. We have used ribosome profiling in mouse liver to measure the translation of mRNAs into protein around-the-clock and at high temporal and nucleotide resolution. Transcriptome-wide, we discovered extensive rhythms in ribosome occupancy, and identified a core set of ˜150 mRNAs subject to particularly robust daily changes in translation efficiency. Cycling proteins produced from non-oscillating transcripts revealed thus far unknown rhythmic regulation associated with specific pathways (notably in iron metabolism, through the rhythmic translation of transcripts containing iron responsive elements), and indicated feedback to the rhythmic transcriptome through novel rhythmic transcription factors. Moreover, estimates of relative levels of core clock protein biosynthesis that we deduced from the data explained known features of the circadian clock better than did mRNA expression alone. Finally, we identified uORF translation as a novel regulatory mechanism within the clock circuitry. Consistent with the occurrence of translated uORFs in several core clock transcripts, loss-of-function of Denr, a known regulator of re-initiation after uORF usage and of ribosome recycling, led to circadian period shortening in cells. In summary, our data offer a framework for understanding the dynamics of translational regulation, circadian gene expression, and metabolic control in a solid mammalian organ. Overall design: A total of 48 mice were entrained under 12hours light:dark conditions for 2 weeks and also collected under 12hours light:dark. Mice were sacrificed every two hours during the 24 hours daily cycle. Two replicates per time point, each replicate is a pool of 2 livers.
Diurnal Oscillations in Liver Mass and Cell Size Accompany Ribosome Assembly Cycles.
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View SamplesClonal cellular variance often confounds reproducibility of forward and reverse genetic studies. We developed combinatorial approaches for whole genome saturated mutagenesis using haploid murine ES cells to permit induction and reversion of genetic mutations. Using these systems, we created a biobank with over 100000 individual ES cell lines with repairable and genetically bar coded mutations targeting 16950 genes. This biobank termed “Haplobank” is freely available. In addition, we developed a genetic color coding system for rapid repair of mutations and direct functional validation in sister clones. Using this system, we report functional validation of essential ES cell genes. We also identified phospholipase16G as a key pathway for cytotoxicity of human rhinoviruses, the most frequent cause of the common cold. Moreover, we derived 3D blood vessel organoids from haploid ES cells, combining conditional mutagenesis in haploid ES cells with tissue engineering. We identified multiple novel genes, such as Connexin43/Gja1, in blood vessel formation and tip cell specification in vitro and also in vivo. Taken together, we develop a conditional homozygous ES cell resource for the community to empower controlled genetic studies in murine ES cells and tissues derived from it. Overall design: RNA-Seq was carried out using standard protocols. https://www.haplobank.at/ecommerce/control/haplobank_resource
Comparative glycoproteomics of stem cells identifies new players in ricin toxicity.
Subject
View SamplesAdenosine-to-inosine (A-to-I) RNA editing, which is catalyzed by a family of adenosine deaminase acting on RNA (ADAR) enzymes, is important in the epitranscriptomic regulation of RNA metabolism. However, the role of A-to-I RNA editing in vascular disease is unknown. Here we show that cathepsin S mRNA (CTSS), which encodes a cysteine protease associated with angiogenesis and atherosclerosis, is highly edited in human endothelial cells. The 3' untranslated region (3' UTR) of the CTSS transcript contains two inverted repeats, the AluJo and AluSx+ regions, which form a long stem–loop structure that is recognized by ADAR1 as a substrate for editing. RNA editing enables the recruitment of the stabilizing RNA-binding protein human antigen R (HuR; encoded by ELAVL1) to the 3' UTR of the CTSS transcript, thereby controlling CTSS mRNA stability and expression. In endothelial cells, ADAR1 overexpression or treatment of cells with hypoxia or with the inflammatory cytokines interferon-? and tumor-necrosis-factor-a induces CTSS RNA editing and consequently increases cathepsin S expression. ADAR1 levels and the extent of CTSS RNA editing are associated with changes in cathepsin S levels in patients with atherosclerotic vascular diseases, including subclinical atherosclerosis, coronary artery disease, aortic aneurysms and advanced carotid atherosclerotic disease. These results reveal a previously unrecognized role of RNA editing in gene expression in human atherosclerotic vascular diseases. Overall design: 1) Evaluation of transcriptome expression and RNA editing sites (A-to-G and T-to-C nucleotide mismatches) in poly(A) RNA-seq data derived from endothelial cell transcriptome after ADAR1 or ADAR2 knockdown (n=2 biological replicates per condition, total n=8 biological samples). 2) Evaluation of transcriptome expression and RNA editing sites (A-to-G and T-to-C nucleotide mismatches) in total-RNA-seq data derived from peripheral blood mononuclear cells (n=12 total biological samples; n=4 replicates per condition). 3) Evaluation of transcriptome expression and RNA editing sites (A-to-G and T-to-C nucleotide mismatches) in total-RNA-seq data derived from endothelial cell transcriptome under basal and hypoxic conditions (n=2 biological replicates per condition, total n=4 biological samples). 4) Evaluation of RNA editing sites (A-to-G and T-to-C nucleotide mismatches) in total RNA-seq data derived from endothelial cell transcriptome under basal and hypoxic conditions after ADAR1 knockdown (n=3 replicates per condition, total n=12 biological samples). 5) HuR iCLIP RNA-sequencing data derived from HUVEC HuR iCLIP after ADAR1 knockdown (scrambled control and siADAR1, n=1 per condition, total n=2 biological samples).
Adenosine-to-inosine RNA editing controls cathepsin S expression in atherosclerosis by enabling HuR-mediated post-transcriptional regulation.
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View SamplesGenetic variation governs protein expression through both transcriptional and post-transcriptional processes. To investigate this relationship, we combined a multiplexed, mass spectrometry-based method for protein quantification with an emerging mouse model harboring extensive genetic variation from 8 founder strains. We collected genome-wide mRNA and protein profiling measurements to link genetic variation to protein expression differences in livers from 192 Diversity Outcross mice. Overall design: Illumina 100bp single-end liver RNA-seq from 192 male and female Diversity Outbred 26-week old mice raised on standard chow or high fat diet. Each sample was sequenced in 2x technical replicates across multiple flowcells. Samples were randomly assigned lanes and multiplexed at 12-24x.
Epistatic Networks Jointly Influence Phenotypes Related to Metabolic Disease and Gene Expression in Diversity Outbred Mice.
Sex, Specimen part, Cell line, Subject
View SamplesWe compared four transcription factor knockdowns using transgenic RNAi expressed in the larval fat body. FOXO, Tfb1, p53, and Stat92E-dependent gene expression in the Drosophila fat body was quantified on control and high-sugar diets in order to generate expression profiles via RNA-seq. These expression data were used to build a gene regulatory network to predict novel roles for these and other genes during caloric overload. Overall design: Control and fat body-expressed transcription factor RNAi Drosophila were reared on control (0.15M sucrose) and high-sugar (0.7M or 1M sucrose) diets until the wandering stage. Fat bodies were isolated and RNA extracted to determine the effects of diet on gene expression using Illumina RNA-seq.
Seven-Up Is a Novel Regulator of Insulin Signaling.
Sex, Specimen part, Treatment, Subject
View SamplesChronic high sugar feeding induces obesity, hyperglycemia, and insulin resistance in flies and mammals. These phenotypes are controlled by the fat body, a liver- and adipose- like tissue in Drosophila flies. To gain insight into the mechanisms underlying the connection between diet and insulin sensitivity, we used Illumina RNA-seq to profile gene expression in fat bodies isolated from chronically high sugar fed, wandering (post-prandial) third instar wild type larvae w(L3). These data were compared to control-fed wild-type wL3 fat bodies as well as those expressing transgenic interfering RNA (i) targeting CG18362 (Mio/dChREBP) in the fat body on both diets. Overall design: Female VDRC w1118, cgGAL4, UAS-Dcr2 or UAS-ChREBPi(52606), cgGAL4, UAS-Dcr2 wandering third instar larvae were fed control (0.15M) or high (0.7M) sucrose and fat bodies isolated for RNA extraction.
Seven-Up Is a Novel Regulator of Insulin Signaling.
Sex, Specimen part, Subject
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