SnapShot-Seq: a method for extracting genome-wide, in vivo mRNA dynamics from a single total RNA sample
ABSTRACT: mRNA synthesis, processing, and destruction involve a complex series of molecular steps that are incompletely understood. Because the RNA intermediates in each of these steps have finite lifetimes, extensive mechanistic and dynamical information is encoded in total cellular RNA. Here we report the development of SnapShot-Seq, a set of computational methods that allow the determination of in vivo rates of pre-mRNA synthesis, splicing, intron degradation, and mRNA decay from a single RNA-Seq snapshot of total cellular RNA. SnapShot-Seq can detect in vivo changes in the rates of specific steps of splicing, and it provides genome-wide estimates of pre-mRNA synthesis rates comparable to those obtained via labeling of newly synthesized RNA. We used SnapShot-Seq to investigate the origins of the intrinsic bimodality of metazoan gene expression levels, and our results suggest that this bimodality is partly due to spillover of transcriptional activation from highly expressed genes to their poorly expressed neighbors. SnapShot-Seq dramatically expands the information obtainable from a standard RNA-Seq experiment. These data are total RNA-Seq data, from RNA sequencing of rRNA-depleted total cellular RNA -- except the LCL 4SU data, which derive from 4SU-labeled RNA. Please see the associated paper for more details.
Project description:To identify the activity-induced gene expression programs in inhibitory neurons, we analyzed RNA extracted from cultured E14 mouse MGE-derived neurons (DIV 10) after these cultures were membrane-depolarized for 0, 1 and 6 hrs with 55mM extracellular KCl. Mouse E14 MGE-derived neurons were cultured for 9 days, quieted overnight with TTX and AP-5 and then membrane-depolarized for 0, 1 or 6 hours by raising the extracellular KCl-concentration to 55mM. RNA was then extracted and WT RNA-Seq was performed on ABi SOLiD
Project description:Circadian profile of polyA RNA by RNA-Seq, collected from ClockΔ19 mouse liver at CT22, CT28, CT34, CT40. RNA from three livers pooled per time point. 4 Clock mutant samples with no replicates
Project description:Circadian profile of polyA RNA by RNA-Seq, collected from mouse liver at CT23, CT29, CT35, CT41, CT47, CT53, CT59, CT65. RNA from three livers pooled per time point. 8 wildtype samples with no replicates.
Project description:Spt6 is a highly conserved histone chaperone that interacts directly with both RNA polymerase II and histones to regulate gene expression. To gain a comprehensive understanding of the requirements for this critical factor, we have performed genome-wide analyses of transcription, chromatin structure, and histone modifications in an S. pombe spt6 mutant. Our results demonstrate several dramatic changes to transcription and chromatin structure in the spt6 mutant, including an elevation of antisense transcripts at over 70 percent of all genes and general loss of the +1 nucleosome. Furthermore, Spt6 is required for the trimethylation of histone H3 on lysines 4 and 36, marks associated with active transcription. Taken together, our results indicate that Spt6 is critical for the accuracy of transcription and the integrity of chromatin, likely via its direct interactions with RNA polymerase II and histones. RNA-seq experiments were performed on wild type and spt6-1 strains in replicate
Project description:We were interested in identifying novel splice junctions in Hep3B cells, especially in genes involved in cholesterol metabolism like HMGCR, so we sequenced polyA-tailed RNA from Hep3B cells. 1 polyA-selected RNA sample was sequenced from Hep3B cells
Project description:Autism spectrum disorder (ASD) is a common, highly heritable neurodevelopmental condition characterized by marked genetic heterogeneity. Thus, a fundamental question is whether autism represents an aetiologically heterogeneous disorder in which the myriad genetic or environmental risk factors perturb common underlying molecular pathways in the brain. Here, we demonstrate consistent differences in transcriptome organization between autistic and normal brain by gene co-expression network analysis. Remarkably, regional patterns of gene expression that typically distinguish frontal and temporal cortex are significantly attenuated in the ASD brain, suggesting abnormalities in cortical patterning. We further identify discrete modules of co-expressed genes associated with autism: a neuronal module enriched for known autism susceptibility genes, including the neuronal specific splicing factor A2BP1 (also known as FOX1), and a module enriched for immune genes and glial markers. Using high-throughput RNA sequencing we demonstrate dysregulated splicing of A2BP1-dependent alternative exons in the ASD brain. Moreover, using a published autism genome-wide association study (GWAS) data set, we show that the neuronal module is enriched for genetically associated variants, providing independent support for the causal involvement of these genes in autism. In contrast, the immune-glial module showed no enrichment for autism GWAS signals, indicating a non-genetic aetiology for this process. Collectively, our results provide strong evidence for convergent molecular abnormalities in ASD, and implicate transcriptional and splicing dysregulation as underlying mechanisms of neuronal dysfunction in this disorder. To identify potential A2BP1-dependent differential splicing events in ASD brain, we performed high-throughput RNA sequencing (RNA-Seq) on three autism samples with significant downregulation of A2BP1 (average fold change by quantitative RT-PCR = 5.9) and three control samples with average A2BP1 levels. The list of potential A2BP1-depending differential splicing events in ASD is given in the Supplementary file linked at the foot of this record.
Project description:Thousands of human genes contain introns ending in NAGNAG motifs (N any nucleotide), where both NAGs can function as 3' splice sites, yielding isoforms differing by inclusion/exclusion of just three bases. However, the functional importance of NAGNAG alternative splicing is highly controversial. Using very deep RNA-Seq data from sixteen human and eight mouse tissues, we found that approximately half of alternatively spliced NAGNAGs undergo tissue-specific regulation and that regulated events have been selectively retained: alternative splicing of strongly tissue-specific NAGNAGs was ten times as likely to be conserved between species as for non-tissue-specific events. Further, alternative splicing of human NAGNAGs was associated with an order of magnitude increase in the frequency of exon length changes at orthologous mouse/rat exon boundaries, suggesting that NAGNAGs accelerate exon evolution. Together, our analyses show that NAGNAG alternative splicing constitutes a major generator of tissue-specific proteome diversity and accelerates evolution of proteins at exon-exon boundaries. mRNA-Seq of sixteen human and eight mouse tissues. Supplementary files: human.nagnag.junctions.gff and mouse.nagnag.junctions.gff are the annotation files (in GFF3 format) corresponding to the 'bwtout' mapped reads files linked to the Sample records. Raw data files provided for Samples GSM742937-GSM742952 only.
Project description:we analyzed globally the effect of exosome processing on the nuclear pre-mRNA transcripts by inactivating either the RRP41 or DIS3 subunit of the exosome. Using SOLiD RNA sequencing technology, we report 30-120 million mapped cellular compartment specific reads per sample allowing the detection of unspliced pre-mRNAs. We show that RRP41 and DIS3 knockdowns stabilize an overlapping set of U12-type introns. Studying the global effect of the exosome (Rrp41 or Dis3 subunit) knockdown comparing to the control sample.
Project description:RNA synthesis and decay rates determine the steady-state levels of cellular RNAs. Metabolic tagging of newly transcribed RNA by 4-thiouridine (4sU) can reveal the relative contributions of RNA synthesis and decay rates. The kinetics of RNA processing, however, so far remained unresolved. Here, we show that ultra-short 4sU-tagging not only provides snap-shot pictures of eukaryotic gene expression but, when combined with progressive 4sU-tagging and RNA-seq, reveals global RNA processing kinetics at nucleotide resolution. Using this method, we identified classes of rapidly and slowly spliced/degraded introns. Interestingly, each class of splicing kinetics was characterized by a distinct association with intron length, gene length and splice site strength. For a large group of introns, we also observed long lasting retention in the primary transcript, but efficient secondary splicing or degradation at later time points. Finally, we show that processing of most, but not all small nucleolar (sno)RNA-containing introns is remarkably inefficient with the majority of introns being spliced and degraded rather than processed into mature snoRNAs. In summary, our study yields unparalleled insights into the kinetics of RNA processing and provides the tools to study molecular mechanisms of RNA processing and their contribution to the regulation of gene expression. 4sU-tagging was performed in human DG75 B-cells by adding 500 uM 4sU to cell culture medium for 5, 10, 15, 20 or 60 min. Following isolation of total cellular RNA, this was separated into nascent and untagged, pre-existing RNA. Nascent RNA as well as total and untagged RNA from 60 min 4sU-tagging were subjected to SOLiD sequencing (SOLiD II) obtaining 35 nt reads.
Project description:Nonsense-mediated mRNA decay (NMD) functions to degrade transcripts bearing premature stop codon (PTC) and is a crucial regulator of gene expression. NMD and the UPF3B gene have been implicated as the cause of various forms of intellectual disability (ID) and other neurological symptoms. Here, we reports three patients with global developmental delay carrying hemizygous deletions of the UPF2 gene, another important member of the NMD pathway and direct interacting partner of UPF3B. Using RNA-SEQ on lymphoblastoid cells from UPF2 deletion patients, we identified 1009 differently expressed genes (DEGs). 38% of these DEGs overlapped with DEGs identified in UPF3B patients. More importantly, 95% of all DEGs in either UPF2 or UPF3B patients share the same trend of de-regulation. This demonstrates that the transcriptome deregulation in these two patient groups is similar and that UPF2 should be considered as a new candidate gene for ID in man. We expanded our inq`uiries and performed a comprehensive search for copy number variations (CNVs) encompassing all NMD genes in cohorts of ID patients and controls. We found that UPF2, UPF3A, Y14, SMG6 and EIF4A3 are frequently deleted and/or duplicated in ID patients. These CNVs are likely to be the root of the problems or to act as predisposing factors. Our results suggest that dosage imbalance of NMD factors is associated with ID and further emphasize the importance of NMD in normal learning and memory processes.