Simultaneous estimation of gene regulatory network structure and RNA kinetics from single cell gene expression
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ABSTRACT: Cells respond to environmental and developmental stimuli by changing their transcriptomes through both regulation of transcription rate and regulated mRNA decay. These biophysical properties determine the transcriptional state of a cell, but measuring them requires metabolic RNA labeling (e.g. 4-thiouracil pulse-chase) to separate RNA decay from synthesis rates. We approach this problem by sequencing individual Saccharomyces cerevisiae cell transcriptomes by continuously sampling from a population without metabolic labeling. Using this continuous-sampling system, we measure expression in 180,000 individual cells both prior to and in response to rapamycin treatment. The rates of change for each transcript can be calculated on a per-cell basis to give smooth, biologically relevant, estimates of RNA velocity. We then train deep learning models to use this transcriptomic and velocity information to make time-dependent predictions about RNA biophysics, and to infer causal regulatory relationships between transcription factors and their genes.
Project description:The goal of this study is to measure Arabidopsis mRNA transcription and mRNA decay rates genome wide at two temperatures, and thus to calculate the temperature coefficient of both processes. Sensing and response to ambient temperature is important for controlling growth and development of many organisms, in part by regulating mRNA levels. mRNA abundance can change with temperature, but it is unclear whether this results from changes to transcription or decay rates and whether passive or active temperature regulation is involved. Results Using a base analogue labelling method we directly measured the temperature coefficient (Q10) of mRNA synthesis and degradation rates of the Arabidopsis transcriptome. We show that for most genes transcript levels are buffered against passive increases in transcription rates by balancing passive increases in the rate of decay. Strikingly, for temperature-responsive transcripts, increasing temperature raises transcript abundance primarily by promoting faster transcription relative to decay and not vice versa, suggesting a global transcriptional mechanism process exists for the activethat controls of mRNA abundance by temperature/ The design of this expreiment is thus: at time zero (dawn) 3 biological replicate samples were harvested, and then the base analogue 4-thiouracil (4SU) was added to three remaining biological replicate samples. At time T these were harvested and the latter biotinylated and separated into 4SU-containing (labelled) and 4SU non-containing (unlabelled) fractions by passage through a streptavidin column. Total RNA for both timepoints was hybridisaed on the chips, as were the separated fractions from time T, giving 12 chips in total. This design was repeated at a second temperature, giving 24 hybridisations. The two tempertaures were 27C and 17C and time T was 1 hour after dawn at 27C and two hours after dawn at 17C.
Project description:Pulse chase measurements using thiouracil (DTU) labeling via UPRT and chasing with uracil Data from tachyzoites is labeled "DTU Pulse Chase". Two independent pulse chase experiments were performed in tachyzoites, pulse chase 1 and 2. Duplicate arrays at each timepoint were performed for pulse chase 2 (2 a and b). Data from bradyzoites are labeled "DTU Bradyzoite Pulse Chase". Two independent pulse chase experiments were performed in bradyzoites and a single set of arrays were performed for each experiment. Just one chase timepoint was used in the bradyzoite experiments, the 2 hour chase. An RNA stablity experiment design type examines stability and/or decay of RNA transcripts. Keywords: RNA_stability_design
Project description:We measure the stability of mRNAs in rapidly dividing yeast by metabolic labeling with thiouracil and determine the effects on mRNA stability in the presence of various inhibitors of translation elongation and initiation.
Project description:To investigate the potential influence of transcription on mRNA stability in mammalian cells, we tested the global relationship between rates of synthesis and decay of mRNAs. We estimated synthesis rates by flash 4sU labeling followed by RNA-seq, and decay rates by treating cells with Actinomycin D (ActD) for 0, 2, 4 and 6 hours and measuring half-lives of all expressed genes by MARS-seq analysis. As short-term perturbations of transcription elongation dynamics diminished mRNA stability, we next wished to examine the effect of extended transcription slowdown. To this end, we treated cells with CPT for 24 hours and profiled mRNA stability in a genome-wide manner using ActD time-course and MARS-seq.
Project description:Eukaryotic mRNAs undergo a cycle of transcription, nuclear export, and degradation. A major challenge is to obtain a global, quantitative view of these processes. Here we measured the genome-wide nucleocytoplasmic dynamics of mRNA in Drosophila cells by metabolic labeling in combination with cellular fractionation. By mathematical modeling of these data we determined rates of transcription, export and cytoplasmic decay for >5,000 genes. We characterized these kinetic rates and investigated links with mRNA features, RNA-binding proteins (RBPs) and chromatin states. We found prominent correlations between mRNA decay rate and transcript size, while nuclear export rates are linked to the size of the 3'UTR. Transcription, export and decay rates are each associated with distinct spectra of RBPs. Specific classes of genes, such as those encoding cytoplasmic ribosomal proteins, exhibit characteristic combinations of rate constants, suggesting modular control. Overall, transcription and decay rates have a major impact on transcript abundance, while nuclear export is of minor importance. Finally, correlations between rate constants suggest global coordination between the three processes. Our approach should be generally applicable to other cell systems and provides insights into the genome-wide nucleocytoplasmic kinetics of mRNA.
Project description:To obtain rates of mRNA synthesis and decay in yeast, we established dynamic transcriptome analysis (DTA). DTA combines non-perturbing metabolic RNA labeling with dynamic kinetic modeling. DTA was used to monitor the cellular response to osmotic stress in comparison to the wild type. Genomic occupancy profiling of RNA polymerase (Pol) II was used to predict changes in mRNA synthesis rates.
Project description:RNA levels detected at steady state are the consequence of multiple dynamic processes within the cell. In addition to synthesis and decay, many transcripts undergo processing. For example, in the case of intron-containing transcripts, there is splicing to take into the equation. Metabolic tagging with a nucleotide analogue is one way of determining the relative contributions of synthesis, decay and conversion processes globally. By using a much refined method of 4-thiouracil labelling in Saccharomyces cerevisiae we can isolate RNA produced during as little as 1 min, allowing the detection of RNA species with high turn-over rates, including intron-containing pre-mRNAs and short-lived non-coding RNAs. Nascent RNA labelled for 1.5, 2.5 or 5 minutes was isolated and analysed by reverse transcriptase-quantitative PCR and RNA sequencing. From these data we measured the relative stability of pre-mRNA species with different high turn-over rates and investigated potential correlations with intron features. This extremely brief metabolic labeling method enables the isolation of short-lived RNA species and the production of transcriptome-wide high-resolution kinetic data with some unexpected results . Previous studies using reporter genes suggested that secondary structure in introns is favourable for efficient splicing and may affect splice site usage. In contrast, our data reveal that ribosomal protein transcripts with intron secondary structures that are predicted to be less stable, splice faster. These data, in combination with previous results, indicate that there is an optimal range of stability of intron secondary structures that allows for rapid splicing.
Project description:Pulse chase measurements using thiouracil (DTU) labeling via UPRT and chasing with uracil Data from tachyzoites is labeled "DTU Pulse Chase". Two independent pulse chase experiments were performed in tachyzoites, pulse chase 1 and 2. Duplicate arrays at each timepoint were performed for pulse chase 2 (2 a and b). Data from bradyzoites are labeled "DTU Bradyzoite Pulse Chase". Two independent pulse chase experiments were performed in bradyzoites and a single set of arrays were performed for each experiment. Just one chase timepoint was used in the bradyzoite experiments, the 2 hour chase. An RNA stablity experiment design type examines stability and/or decay of RNA transcripts. User Defined
Project description:adt12-01_uprt - plant rabt n°1 - Impact of RNA labeling by Plant RABT on plant transcriptome - Determine the incidence of RNA marking by the RABT method Plantation on the plants transcriptome. In several studies Clearly et al. have described a method referred as "4TU tagging" which can be use to study mRNA synthesis and decay either in a mixed population of cells or in a specific cell type (Cleary, Meiering et al. 2005, Zeiner, Cleary et al. 2008, Miller, Robinson et al. 2009, Rabani et al., 2011). Through the specific cell type expression in drosophila and mammalian cells of theToxoplasma gondii uracil PhosphoribosylTransferase activity and the metabolization of the uracil analog 4-thiouracil (4 TU), mRNA were selectively tagged, purified and used in microarray based analysis.