Project description:The control of mRNA stability plays a central role in regulating gene expression patterns. While much is known about the roles of 5´ and 3´ untranslated regions in the mRNA stability control, the impact of protein-coding sequences on mRNA stability had been obscure. Recently, several groups reported that codon composition in the ORF affects mRNA deadenylation and degradation rates in a translation-dependent manner. Hence, codons define not only the amino acid sequences to be synthesized but also the stability of mRNAs. However, how 61 codons differently affect mRNA stability remains unclear. Besides, aberrant stalling of the ribosome induces ribosome quality control (RQC) and No-go decay. The relationship between the two co-translational mRNA decay pathways is not systematically analyzed. To precisely characterize the effects of 61 codons on mRNA stability, we developed a simplified reporter system that allows detection of the effect of every single codon on mRNA stability in zebrafish embryos. Using this system, we show that the effect of codons on mRNA stability is partially but significantly correlated with the translation elongation rate and tRNA abundance. Interestingly, the codon effect is still maintained in zebrafish embryos lacking Znf598, an essential mediator of RQC and NGD. Znf598-dependent NGD targets a particular type of ribosome stalling but has limited impact on endogenous mRNA stability. Our study thus defines two related co-translational mRNA decay pathways during animal development.
Project description:Messenger RNA (mRNA) stability substantially impacts steady-state gene expression levels in a cell. mRNA stability is strongly affected by codon composition in a translation-dependent manner across species, through a mechanism termed codon optimality. We have developed iCodon (www.iCodon.org), an algorithm for customizing mRNA expression through the introduction of synonymous codon substitutions into the coding sequence. iCodon is optimized for four vertebrate transcriptomes: mouse, human, frog, and fish. Users can predict the mRNA stability of any coding sequence based on its codon composition and subsequently generate more stable (optimized) or unstable (deoptimized) variants encoding for the same protein. Further, we show that codon optimality predictions correlate with both mRNA stability using a massive reporter library and expression levels using fluorescent reporters and analysis of endogenous gene expression in zebrafish embryos and/or human cells. Therefore, iCodon will benefit basic biological research, as well as a wide range of applications for biotechnology and biomedicine.
Project description:The control of mRNA stability plays a central role in regulating gene expression. In metazoans, the earliest stages of development are driven by maternally supplied mRNAs. The degradation of these maternal mRNAs is critical for promoting the maternal-to-zygotic transition of developmental programs, although the underlying mechanisms are poorly understood in vertebrates. Here, we characterized maternal mRNA degradation pathways in zebrafish using a transcriptome analysis and systematic reporter assays. Our data demonstrate that ORFs enriched with uncommon codons promote deadenylation by the CCR4-NOT complex in a translation-dependent manner. This codon-mediated mRNA decay is conditional on the context of the 3â² UTR, with long 3â² UTRs conferring resistance to deadenylation. These results indicate that the combined effect of codon usage and 3â² UTR length determines the stability of maternal mRNAs in zebrafish embryos. Our study thus highlights the codon-mediated mRNA decay as a conserved regulatory mechanism in eukaryotes. zebrafish embryonic mRNA profile at 2 different stages (2 hpf and 6 hpf) in wildtype and 3 additional conditions (miR-430 inhibition, RNApol II inhibition and CNOT7 inhibition) at 6 hpf. All experiments are performed as triplicates
Project description:The control of mRNA stability plays a central role in regulating gene expression. In metazoans, the earliest stages of development are driven by maternally supplied mRNAs. The degradation of these maternal mRNAs is critical for promoting the maternal-to-zygotic transition of developmental programs, although the underlying mechanisms are poorly understood in vertebrates. Here, we characterized maternal mRNA degradation pathways in zebrafish using a transcriptome analysis and systematic reporter assays. Our data demonstrate that ORFs enriched with uncommon codons promote deadenylation by the CCR4-NOT complex in a translation-dependent manner. This codon-mediated mRNA decay is conditional on the context of the 3′ UTR, with long 3′ UTRs conferring resistance to deadenylation. These results indicate that the combined effect of codon usage and 3′ UTR length determines the stability of maternal mRNAs in zebrafish embryos. Our study thus highlights the codon-mediated mRNA decay as a conserved regulatory mechanism in eukaryotes.
Project description:Oligodendrocytes are specialized cells that confer neuronal myelination. Leukodystrophies associated with oligodendrocyte and hypomyelination are known to result when a number of tRNA metabolism genes are mutated. Thus, for unknown reasons, oligodendrocytes may be hypersensitive to perturbations in tRNA biology. In this study, we survey the tRNA transcriptome in the murine oligodendrocytes cell lineage in an effort to understanding the molecular underpinning for human disease. We find that specific tRNAs are hypomodified in oligodendrocytes within or near the anticodon. This hypomodified state may be the result of differential expression of key modification enzymes during oligodendrocyte differentiation. Moreover, we observe a concomitant relationship between tRNA hypomodification and tRNA decoding potential; observing oligodendrocyte specific alterations in codon optimality-mediated mRNA decay and ribosome transit. Our results reveal that oligodendrocytes naturally maintain a delicate, hypersensitized tRNA/mRNA axis. We suggest this axis underlies disease etiology when further insult to tRNA metabolism is introduced.
Project description:Oligodendrocytes are specialized cells that confer neuronal myelination. Leukodystrophies associated with oligodendrocyte and hypomyelination are known to result when a number of tRNA metabolism genes are mutated. Thus, for unknown reasons, oligodendrocytes may be hypersensitive to perturbations in tRNA biology. In this study, we survey the tRNA transcriptome in the murine oligodendrocytes cell lineage in an effort to understanding the molecular underpinning for human disease. We find that specific tRNAs are hypomodified in oligodendrocytes within or near the anticodon. This hypomodified state may be the result of differential expression of key modification enzymes during oligodendrocyte differentiation. Moreover, we observe a concomitant relationship between tRNA hypomodification and tRNA decoding potential; observing oligodendrocyte specific alterations in codon optimality-mediated mRNA decay and ribosome transit. Our results reveal that oligodendrocytes naturally maintain a delicate, hypersensitized tRNA/mRNA axis. We suggest this axis underlies disease etiology when further insult to tRNA metabolism is introduced.
Project description:Oligodendrocytes are specialized cells that confer neuronal myelination. Leukodystrophies associated with oligodendrocyte and hypomyelination are known to result when a number of tRNA metabolism genes are mutated. Thus, for unknown reasons, oligodendrocytes may be hypersensitive to perturbations in tRNA biology. In this study, we survey the tRNA transcriptome in the murine oligodendrocytes cell lineage in an effort to understanding the molecular underpinning for human disease. We find that specific tRNAs are hypomodified in oligodendrocytes within or near the anticodon. This hypomodified state may be the result of differential expression of key modification enzymes during oligodendrocyte differentiation. Moreover, we observe a concomitant relationship between tRNA hypomodification and tRNA decoding potential; observing oligodendrocyte specific alterations in codon optimality-mediated mRNA decay and ribosome transit. Our results reveal that oligodendrocytes naturally maintain a delicate, hypersensitized tRNA/mRNA axis. We suggest this axis underlies disease etiology when further insult to tRNA metabolism is introduced.
Project description:Codon optimality mediated decay(COMD) is a conserved phenomenon from yeast to human. Our data suggests that COMD alson exist in neurospora crass. We resort thiolutin(inhibitor for transcription) to treat cells in different time point and transcriptionally profiled them to get the landscape of transpcriptional decay profiling.
Project description:mRNA translation decodes nucleotide into amino acid sequences. However, translation has also been shown to affect mRNA stability depending on codon composition in model organisms, although universality of this mechanism remains unclear. Here, using three independent approaches to measure exogenous and endogenous mRNA decay, we define which codons are associated with stable or unstable mRNAs in human cells. We demonstrate that the regulatory information affecting mRNA stability is encoded in codons and not in nucleotides. Stabilizing codons tend to be associated with higher tRNA levels and higher charged/total tRNA ratios. While mRNAs enriched in destabilizing codons tend to possess shorter poly(A)-tails, the poly(A)-tail is not required for the codon-mediated mRNA stability. This mechanism depends on translation; however, the number of ribosome loads into a mRNA modulates the codon-mediated effects on gene expression. This work provides definitive evidence that translation strongly affects mRNA stability in a codon-dependent manner in human cells. 293T cells and k562 cells were infected with ORFome library to decay exodogenous gene mRNA decay. Stable infected cells were treated with actinmycin D at 6 well plate and samples were collected in duplicate every hour 0-6h for RNA-seq