Project description:For the past decade, extensive studies of translation have produced a vast amount of ribosome profiling data, an insightful resource for mining of critical details about the dynamics of translation regulation under various biological contexts. Previously, Rocaglamide A (RocA), an anti-tumor heterotricyclic natural compound, has been shown to selectively inhibit translation initiation of a large group of mRNA species by clamping eukaryotic translation initiation factor 4A (eIF4A) onto poly-purine motifs in the 5’ un-translational regions (5’UTRs). However, re-analysis of the previous ribosome profiling datasets revealed an unexpected shift of the ribosome occupancy pattern during early translation elongation upon RocA treatment in various types of cells, for a specific group of mRNA transcripts without poly-purine motifs over-presented in their 5’UTRs. Such perturbation of the translation elongation dynamics can be attributed to the blockage of translating ribosomes due to the binding of eIF4A to the poly-purine sequence in coding sequences. This new mode of action of RocA, which is complementary to the canonical function inhibiting translation initiation, selectively interfere with the translation of the genes involved in fundamental processes such as ATP synthase, mitochondrial respiratory chain complex, et al. In summary, re-analyses of previous ribosome profiling data has revealed the complete dual modes of RocA in blocking translation and thus underlying the potent anti-tumor effect
Project description:The ribosome-associated protein quality control (RQC) system that resolves stalled translation events is activated when ribosomes collide and form disome, trisome or higher order complexes. However, it is unclear whether this system distinguishes collision complexes formed on defective mRNAs from those with functional roles on endogenous transcripts. Here, we performed disome and trisome footprint profiling in yeast and found collisions were enriched on diverse sequence motifs known to slow translation. When 60S recycling was inhibited, disomes accumulated at stop codons and could move into the 3’UTR to reinitiate translation. The ubiquitin ligase and RQC factor Hel2/ZNF598 generally recognized collisions but did not trigger degradation of endogenous transcripts. However, loss of Hel2 triggered the integrated stress response, via phosphorylation of eIF2alpha, thus linking these pathways. Our results suggest that Hel2 has a role in sensing ribosome collisions on endogenous mRNAs and such events may be important for cellular homeostasis.
Project description:Monosome and disome profiling was performed on Flag-STAU1 Flp-In 293 T-REx to study the causes of ribosomal collisions, and whether this may be modulated by the presence/absence of Staufen-1. Cells were treated with either an siRNA targeting STAU1 transcript (4x samples) or a control siRNA (2x samples). Two of the four samples treated with the STAU1 siRNA had siRNA-resistant STAU1 mRNA expression induced by doxycycline (rescue). Sequencing libraries from monosome and disome fractions were generated in parallel from the same samples. Note that unique molecular identifiers/random barcodes (UMIs/RBCs) were included in the sequencing experiment. Each UMI has been moved to the fastq read name of each read. For example \\"xxxxxxrbc:AGCCAAT\\" in the read name signifies that the given read had a UMI of \\"AGCCAAT\\". Using these UMIs, PCR duplicates can be removed with UMI-Tools following read alignment.
Project description:Purpose: To explore the molecular mechanisms of ISLR protein, RNA sequencing was performed to analyze the geome-wide change of ISLR secreted supernatant treated HEK293FT cells compared to those of control supernatant treated cells. Methods: Total mRNA was extracted from HEK293FT cells in triplicate respectively. Then RNA quality was assessed using an Agilent Bioanalyzer 2100 and the sample reads were sequenced using Illumina Hiseq 4000 platform. As a reasult, we got the transcript data using Hisat2 followed by Stringtie. qRT–PCR validation was performed using TaqMan and SYBR Green assays. Results: We mapped about 60 million sequence reads per sample to the human genome and identified about 58,000 transcripts in HEK293FT cells. Many transcripts showed different expression between ISLR secreted supernatant and control treated HEK293FT cells, with a fold change ≥2 and p value <0.05. Gene set enrichment analysis (GSEA) showed a significantly positive enrichment of Hippo target genes. Conclusion: Our study present the datiled transcripts analysis of HEK293FT cells, with biologic replicates. Based on RNA-seq transcriptome characterization , we conclude a molecular mechanism of ISLR regulating multiple pathways related to tissue repair.
Project description:Transcriptomic analysis of synchonized AC16 cells treated with homoharringtonine 1 µM or Rocaglamide A 100 nM for 4h (20h after synchronization) We used microarrays to detail the global programme of gene expression
Project description:Rocaglamide A (RocA) typifies a novel class of protein synthesis inhibitors that selectively kill aneuploid tumor cells and repress translation of specific mRNAs. RocA targets eukaryotic initiation factor 4A (eIF4A), the prototypical DEAD-box RNA helicase, and its mRNA selectivity is proposed to reflect highly structured 5â² UTRs that are very dependent on eIF4A-mediated unwinding. Here, we show that secondary structure in 5â² UTRs is only a minor determinant for RocA selectivity and RocA does not repress translation by reducing eIF4A activity. Rather, in vitro and in vivo, RocA clamps eIF4A onto a specific sequence motif even after ATP hydrolysis. This artificially clamped eIF4A blocks 43S scanning, leading to premature, upstream translation initiation and reducing gene expression on transcripts bearing the RocA-eIF4A target sequence. In elucidating the mechanism of this lead anti-cancer compound and explaining its mRNA selectivity, we provide the first example of a drug stabilizing sequence-specific RNA-protein interactions. Ribosome profiling, mRNA-Seq, RIP-Seq, and Bind-n-Seq Ribosome profiling for sample 1-5, and 11-15. Sample1 and 2 are replicates of control of DMSO treatment for sample 3-5, and 11, with RocA and PP242 treatments. Sample 12 and 13 are replicates of control of DMSO treatment for sample 14 and 15 with Hipp treatments. mRNA-Seq for sample 6-10. Sample 6 and 7 are replicates of control of DMSO treatment for sample 8-10 with RocA treatments. RIP-Seq for 16-19. Sample 16 and 17 are replicates of control of DMSO treatment for sample 18-19 with RocA treatments. Bind-n-Seq for 20-23. Sample 21 is control of DMSO treatment for sample 22-23 with RocA treatments. Sample 20 is a input contol for protein-bound fraction of sample 21. We stably expressed SBP (streptavidin binding peptide)-tagged eIF4A in HEK 293T-REx cells and purified it via M270 streptavidin beads (life techonologies).