Post-transcriptional regulation plays a crucial role in shaping gene expression. During the Maternal-to-Zygotic Transition (MZT), thousands of maternal transcripts are regulated, however, how different cis-elements and trans-factors are integrated to determine mRNA stability is still poorly understood. Here, we show that most transcripts are under combinatorial regulation by multiple decay pathways during zebrafish MZT. Using a massively parallel reporter assay, we identified cis-regulatory sequences in the 3'-UTR, including poly-U motifs that are associated with mRNA stability. In contrast, miR-430 target sequences, UAUUUAUU AU-rich elements (ARE), CCUC and CUGC elements emerged as destabilizing motifs, with miR-430 and AREs causing mRNA deadenylation upon genome activation. We identified trans-factors by profiling RNA-protein interactions and found that poly-U binding proteins are preferentially associated with 3'-UTR sequences and stabilizing motifs. We demonstrate that this activity is antagonized by poly-C motifs and correlated with protein binding. Finally, we integrated these regulatory motifs into a machine learning model that predicts reporter mRNA stability in vivo.This is the developmental mRNA-seq timecourse part of the study.
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Sex, Age, Specimen part, Cell line, Treatment
View SamplesRNA folding plays a crucial role in RNA function. However, our knowledge of the global structure of the transcriptome is limited to steady-state conditions, hindering our understanding of how RNA structure dynamics influences gene function. Here, we have characterized mRNA structure dynamics during the maternal-to-zygotic transition in zebrafish. We observe that on a global level, translation guides structure rather than structure guides translation. We detect a decrease in structure in translated regions, and identify the ribosome as a major remodeler of RNA structure in vivo. In contrast, we find that 3'-UTRs form highly folded structures in vivo, which can affect gene expression by modulating miRNA activity. Furthermore, we find that dynamic 3'-UTR structures are enriched in RNA decay elements, including regulatory elements in nanog, and cyclin A1, key maternal factors orchestrating the maternal-to-zygotic transition. These results reveal a central role of RNA structure dynamics in gene regulatory programs during embryogenesis.This is the developmental mRNA-seq timecourse part of the study.
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Sex, Age, Specimen part, Cell line, Treatment
View SamplesGene expression is regulated extensively at the level of mRNA stability, localization, and translation. However, decoding functional RNA regulatory features remains a limitation to understanding post-transcriptional regulation in vivo. Here, we developed RNA Element Selection Assay (RESA), a method that selects RNA elements based on their activity in vivo and uses high-throughput sequencing to provide quantitative measurement of their regulatory function with near nucleotide resolution. We implemented RESA to identify sequence elements modulating mRNA stability during zebrafish embryogenesis. RESA provides a sensitive and quantitative measure of microRNA activity in vivo and also identifies novel regulatory sequences. To uncover specific sequence requirements within regulatory elements, we developed a bisulfite-mediated nucleotide conversion strategy for large-scale mutational analysis (RESA-bisulfite). Finally, we used the versatile RESA platform to map candidate protein-RNA interactions in vivo (RESA-CLIP). The RESA platform can be broadly applicable to uncover the regulatory features shaping gene expression and cellular function.
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View SamplesAmputation of heart tissue followed by regeneration of the heart. Samples were taken at 0 hpa (hours post-amputation), 6 hpa, 12 hpa, 24 hpa, 3 dpa and 5 dpa.
Simplet controls cell proliferation and gene transcription during zebrafish caudal fin regeneration.
Specimen part, Time
View SamplesPre-mRNA splicing is a critical step of gene expression in eukaryotes. Transcriptome-wide splicing patterns are complex and primarily regulated by a diverse set of recognition elements and associated RNA-binding proteins. The retention and splicing (RES) complex is formed by three different proteins (Bud13p, Pml1p and Snu17p) and is involved in splicing in yeast. However, the importance of the RES complex for vertebrate splicing, the intronic features associated with its activity, and its role in development are unknown. In this study, we have generated loss-of-function mutants for the three components of the RES complex in zebrafish and showed that they are required during early development. The mutants showed a marked neural phenotype with increased cell death in the brain and a decrease in differentiated neurons. Transcriptomic analysis of bud13, snip1 (pml1) and rbmx2 (snu17) mutants revealed a global defect in intron splicing, with strong mis-splicing of a subset of introns. We found these RES-dependent introns were short, rich in GC and flanked by GC depleted exons, all of which are features associated with intron definition. Using these features, we developed and validated a predictive model that classifies RES dependent introns. Altogether, our study uncovers the essential role of the RES complex during vertebrate development and provides new insights into its function during splicing.
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Sex, Age, Specimen part, Cell line
View SamplesMolecular prognostic assays, such as Oncotype DX, are increasingly incorporated into the management of patients with invasive breast carcinoma. BreastPRS is a new molecular assay developed and validated from a meta-analysis of publically available genomic datasets. We applied the assay to matched fresh-frozen (FF) and formalin-fixed paraffin embedded (FFPE) tumor samples to translate the assay to FFPE. A linear relationship of the BreastPRS prognostic score was observed between tissue preservation formats. BreastPRS recurrence scores were compared with Oncotype DX recurrence scores from 246 patients with invasive breast carcinoma and known Oncotype DX results. Using this series, a 120-gene linear discriminant algorithm (LDA) was trained to predict Oncotype DX risk groups and then applied to series of untreated, node-negative, estrogen receptor (ER) positive patients from previously published studies with known clinical outcomes. Correlation of recurrence score and risk group between Oncotype DX and BreastPRS was statistically significant (P<0.0001). 59 of 260 (23%) patients from four previously published studies were classified as intermediate-risk when the 120-gene LDA was applied. BreastPRS reclassified the 59 patients into binary risk groups (high vs. low-risk). 23 (39%) patients were classified as low-risk 36 (61%) as high-risk [P=0.029, HR: 3.64, 95% CI: 1.40 to 9.50]. At 10 years from diagnosis, the low-risk group had a 90% recurrence-free survival (RFS) rate, compared to 60% for the high-risk group. BreastPRS recurrence score is comparable to Oncotype DX and can reclassify Oncotype DX intermediate-risk patients into two groups with significant differences in RFS. Further studies are needed to validate these findings.
BreastPRS is a gene expression assay that stratifies intermediate-risk Oncotype DX patients into high- or low-risk for disease recurrence.
Disease stage
View SamplesMicroarray technologies allow the identification of large numbers of expression differences within and between species. Although environmental and physiological stimuli are clearly responsible for changes in the expression levels of many genes, it is not known whether the majority of changes of gene expression fixed during evolution between species and between various tissues within a species are caused by Darwinian selection or by stochastic processes. We find the following: (1) expression differences between species accumulate approximately linearly with time; (2) gene expression variation among individuals within a species correlates positively with expression divergence between species; (3) rates of expression divergence between species do not differ significantly between intact genes and expressed pseudogenes; (4) expression differences between brain regions within a species have accumulated approximately linearly with time since these regions emerged during evolution. These results suggest that the majority of expression differences observed between species are selectively neutral or nearly neutral and likely to be of little or no functional significance. Therefore, the identification of gene expression differences between species fixed by selection should be based on null hypotheses assuming functional neutrality. Furthermore, it may be possible to apply a molecular clock based on expression differences to infer the evolutionary history of tissues.
A neutral model of transcriptome evolution.
Sex, Age, Specimen part, Disease, Disease stage
View SamplesNewcastle disease virus (NDV) is an avian virus that selectively replicates and kills many different types of cancer cells and is being developed for cancer treatment. Our aim was to establish persistent infection in EJ28 and TCCSUP bladder cancer cells and identify the dysregulated genes and disrupted molecular pathways associated with persistent infection.
No associated publication
Sex, Age, Specimen part, Disease, Cell line
View SamplesZebrafish embryo animal cap explants were differentiated by injection of vhnf1 mRNA into the one-cell stage embryo, and treatment of excised explants with applied FGF8 protein. To identify unique targets of the combination of vhnf1+FGF8, each factor was applied alone and in combination, and differences in gene expression used to identify unique targets of vhnf1+FGF8.
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Specimen part, Compound
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