Project description:Charcot-Marie-Tooth (CMT) disease can be caused by mutations in Aminoacyl-tRNA-Synthetases, including G240R mutation in Glycyl-tRNA-Synthetase (GARS). Ribo-seq generates snapshots of translating ribosomes on mRNA and therefore allows analysis of ribosome pausing mRNA. Here we performed Ribo-seq on lysates of HEK293T cells overexpressing GARS, WT or G240R, to dissect mechanism of CMT linked with translation. We found that GARS G240R causes pausing of ribosomes with glycine codons in A-site. The effect is specific for 21 nt ribosome-protected fragments, produced by ribosomes with empty A-sites, suggestive of the deficit of charged Glycyl-tRNA in GARS G240R-CMT.
Project description:We present results of RNA-Seq, Ribo-Seq, and RIP-Seq (YB-1, YB-3) experiments performed in HEK293T cells, as well as in HEK293T cells with YB-1 knockout and overexpression. The data shows YB-1 function as a global translation inhibitor and YB-3 ability to substitute YB-1 in its function in YB-1 knockout mutant.
Project description:To explore the binding sites of PTENα on viral or host RNAs, we performed HyperTRIBE assay of HEK293T cells overexpressing ADAR1-CD, PTENα-N(WT)-ADAR1-CD, or PTENα-N(6R/D)-ADAR1-CD fusion protein under VSV-GFP (green fluorescent protein-expressing vesicular stomatitis virus) infection.
Project description:RNA-seq experiment to study the role of Pat1b in HEK293T cells. HEK293T cells were treated twice with siRNA with Lipofectamine 2000 then harvested after 48hours. Total RNA was extracted with TriReagent. Ribo-Zero TruSeq stranded mRNA libraries were prepared for each sample and sequenced on Illumina NextSeq 500 Sequencing System providing around 100 million reads per sample (around 75 bp paired-end reads).
Project description:mRNAs are generally assumed to be loaded instantly with ribosomes upon entry into the cytoplasm. To measure ribosome density on nascent mRNA, we developed nascent Ribo-Seq (nRibo-Seq) by combining Ribo-Seq with progressive 4-thiouridine labelling. In mouse macrophages, we experimentally determined, for the first time, the lag between the appearance of nascent RNA and its association with ribosomes, which was calculated to be 20 - 22 min for bulk mRNA, and approximated the time it takes for mRNAs to be fully loaded with ribosomes to be 41 - 44 min. Notably, ribosomal loading time is adapted to gene function as rapid loading was observed with highly regulated genes. The lag and ribosomal loading time correlate positively with ORF size and mRNA half-life, and negatively with tRNA adaptation index. Similar results were obtained in mouse embryonic stem cells, where the lag in ribosome loading was even more pronounced with 35 - 38 min. We validated our measurements after stimulation of macrophages with lipopolysaccharide, where the lag between cytoplasmic and translated mRNA leads to uncoupling between input and ribosome-protected fragments. Uncoupling is stronger for mRNAs with long ORFs or half-lives, a finding we also confirmed at the level of protein production by nascent chain proteomics. As a consequence of the lag in ribosome loading, ribosome density measurements are distorted when performed under conditions where mRNA levels are far from steady state expression, and transcriptional changes affect ribosome density in a passive way. This study uncovers an unexpected and considerable lag in ribosome loading, and provides guidelines for the interpretation of Ribo-Seq data taking passive effects on ribosome density into account.