The RNA methyltransferase METTL8 installs m3C32 in mitochondrial tRNAsThr/Ser(UCN) to optimise tRNA structure and mitochondrial translation
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ABSTRACT:
PROVIDER: PRJNA767378 | ENA |
REPOSITORIES: ENA
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Project description:Modified nucleotides in tRNAs are important determinants of folding, structure and function. Here, we identify METTL8 as a mitochondrial matrix protein and active RNA methyltransferase responsible for installing m3C32 in the human mitochondrial (mt-)tRNAThr and mt-tRNASer(UCN). METTL8 crosslinks to the anticodon stem loop (ASL) of many mt-tRNAs in cells, raising the question of how methylation target specificity is achieved. Dissection of mt-tRNA recognition elements revealed U34G35 and t6A37/(ms2)i6A37, present concomitantly only in the ASLs of the two substrate mt-tRNAs, as key determinations for METTL8-mediated methylation of C32. Several lines of evidence demonstrate the influence of U34, G35, and the m3C32 and t6A37/(ms2)i6A37 modifications in mt-tRNAThr/Ser(UCN) on the structure of these mt-tRNAs. Although mt-tRNAThr/Ser(UCN) lacking METTL8-mediated m3C32 are efficiently aminoacylated and associate with mitochondrial ribosomes, mitochondrial translation is mildly impaired by lack of METTL8. Together these results define the cellular targets of METTL8 and shed new light on the role of m3C32 within mt-tRNAs.
2021-12-04 | GSE185015 | GEO
Project description:Modified nucleotides in tRNAs are important determinants of folding, structure and function. Here, we identify METTL8 as a mitochondrial matrix protein and active RNA methyltransferase responsible for installing m3C32 in the human mitochondrial (mt-)tRNAThr and mt-tRNASer(UCN). METTL8 crosslinks to the anticodon stem loop (ASL) of many mt-tRNAs in cells, raising the question of how methylation target specificity is achieved. Dissection of mt-tRNA recognition elements revealed U34G35 and t6A37/(ms2)i6A37, present concomitantly only in the ASLs of the two substrate mt-tRNAs, as key determinations for METTL8-mediated methylation of C32. Several lines of evidence demonstrate the influence of U34, G35, and the m3C32 and t6A37/(ms2)i6A37 modifications in mt-tRNAThr/Ser(UCN) on the structure of these mt-tRNAs. Although mt-tRNAThr/Ser(UCN) lacking METTL8-mediated m3C32 are efficiently aminoacylated and associate with mitochondrial ribosomes, mitochondrial translation is mildly impaired by lack of METTL8. Together these results define the cellular targets of METTL8 and shed new light on the role of m3C32 within mt-tRNAs.
2021-12-04 | GSE174448 | GEO
Project description:The RNA methyltransferase METTL8 installs m3C32 in mitochondrial tRNAsThr/Ser(UCN) to optimise tRNA structure and mitochondrial translation
| PRJNA731102 | ENA
Project description:Expression of selenoproteins requires the co-translational incorporation of selenocysteine (Sec) in response to an in-frame UGA codon. The machinery of UGA/Sec re-coding is complex and many factors affect the hierarchy of expression among selenoproteins, including modification of tRNA[Ser]Sec. Its hyper-modification in the anticodon stem loop is influenced by selenium bioavailability, and a mutation in adenosine 37 (A37) that abrogates isopentenylation, has a profound effect on selenoprotein expression in mice. Patients with mutations in tRNA-isopentenyl-transferase (TRIT1) show a severe neurological disorder and hence we wondered whether mutations in TRIT1 negatively affected the expression of selenoproteins. Fibroblasts from a patient carrying a pathogenic R323Q mutation in TRIT1 in homozygosity did not show decreased selenoprotein expression, although recombinant TRIT1R323Q had significantly reduced activity in vitro towards anticodon stem-loop substrates. We thus engineered mice conditionally deficient in Trit1 in hepatocytes and neurons. Selenoprotein expression as assessed by western blotting, 75Se metabolic labeling, and ribosomal profiling was not decreased despite the general reduction of N6-isopentenyl-adenosine in tRNAs. We show that 5-methylcarboxymethylation and 2’O-methylation of U34 occur independently of isopentenylation of A37 in tRNA[Ser]Sec. Reanalyzing previously published ribosomal profiling datasets, we demonstrate that (i) failure of 5-carboxymethylation at U34 is associated with reduced expression of GPX1, but not GPX4, and that (ii) FTSJ1 is not the elusive U34-2’O-methyltransferase involved in the methylation of tRNA[Ser]Sec.
2021-11-17 | GSE183923 | GEO
Project description:Increasing evidence implicates critical roles of various epitranscriptomic RNA modifications in different biological processes. Methyltransferase METTL8 installs 3-methylcytosine modification of mitochondrial tRNAs in vitro, however, its role in intact biological systems is completely unknown. Here we show that Mettl8 is localized in the mitochondria and installs m3C in mitochondrial tRNASer(UCN)/Thr in mouse embryonic cortical neural stem cells. At molecular and cellular levels, Mettl8 deletion in cortical neural stem cells leads to reduced mitochondrial protein translation and attenuated respiration activity. At the functional level, conditional Mettl8 deletion in mice results in impaired embryonic cortical neural stem cell maintenance in vivo, which can be rescued by pharmacologically enhancing mitochondrial functions. Similarly, METTL8 regulates mitochondrial protein expression and neural stem cell maintenance in human forebrain cortical organoids. Together, our study reveals a conserved epitranscriptomic mechanism of Mettl8 and mitochondrial tRNA m3C modification in maintaining embryonic cortical neural stem cells in mice and humans.
2023-01-12 | GSE214445 | GEO
Project description:Mitochondria contain a specific translation machinery for the synthesis of respiratory chain components encoded on the mitochondrial genome. Mitochondrial tRNAs (mt-tRNAs) are also generated from the mitochondrial genome and, similar to their cytoplasmic counterparts, are modified at various positions. Here, we find that the RNA methyltransferase METTL8, is a mitochondrial protein that facilitates m3C methylation at position C32 of mt-tRNASer(UCN) and mt-tRNAThr. METTL8 knock out cells show reduced and over expressing cells enhanced respiratory chain activity. In pancreatic cancer, METTL8 levels are high, which correlates with patient survival. Indeed, METTL8 up regulation stimulates respiratory chain activity in these cells. Ribosome occupancy analysis using ribosome profiling revealed ribosome stalling on mt-tRNASer(UCN) and mt-tRNAThr codons and mass spectrometry analysis of native ribosomal subcomplexes unraveled reduced respiratory chain incorporation of the mitochondria encoded proteins ND6 and ND1. A well-balanced translation of mt-tRNASer(UCN) and mt-tRNAThr codons through METTL8-mediated C32 methylation might therefore provide optimal respiratory chain compositions and function.
2023-01-02 | GSE180400 | GEO
Project description:Editing of mischarged tRNAs by cytoplasmic aminoacyl-tRNA synthetases (aaRSs) is of high significance for protein homeostasis, whose impairment causes neurodegeneration. However, whether mitochondrial translation needs fidelity and the significance of proofreading (editing) by mitochondrial aaRSs are long-term mysteries. Here, we showed that NIH-3T3 cell line critically depend on the editing of mitochondrial threonyl-tRNA synthetase (Tars2) editing, the disruption of which accumulated Ser-tRNAThr and generated a large abundance of Thr-to-Ser misincorporated peptides. Such infidelity impaired mitochondrial translation and oxidative phosphorylation, causing oxidative stress and cell cycle arrest at G0/G1 phase. ROS removal by N-acetylcysteine relieved abnormal cell proliferation.
2023-08-25 | GSE232410 | GEO
Project description:To investigate differential mitochondrial tRNA gene expression in wild type (WT) and mutant (E423P) mitochondrial RNA polymerase (POLRMT) overexpression flies, we performed Drsophila mitochondrial tRNA-seq according to the Hydro-tRNAseq method. tRNA-seq reads were subjected to 3' - adapter filtering , 3' - adapter trimming and quality control. The tRNAs expression levels were measured by tag count. For each tRNA sequence-based profile, the mapped reads number used to estimate the expression level of each tRNA. The tRNAs expression profiling was calculated based on uniquely mapped reads and including mapped reads, respectively. We found no difference in the relative abundance of mitochondrial individual tRNAs between WT and E423P overexpression flies.
2021-01-06 | GSE164324 | GEO
Project description:Mature tRNA pools were measured using an adaptation of Y-shaped Adapter-ligated MAture tRNA sequencing (YAMAT-seq) (Shigematsu et al., 2017) in nine strains derived from the model bacterium, Pseudomonas fluorescens SBW25. The aim of the experiment was to determine the effect on the mature tRNA pool of (i) removing the single-copy serCGA gene by genetic engineering, and (ii) duplicating the serTGA gene during a subsequent, compensatory evolution experiment. We found that (i) results in the loss of tRNA-Ser(CGA) from the mature tRNA pool, and (ii) results in a 2-fold higher expression of tRNA-Ser(UGA). tRNA-Ser(UGA) presumably substitutes for tRNA-Ser(CGA) by wobble base pairing to translate codon 5'-UCG-3'.
2020-11-02 | GSE144791 | GEO
Project description:tRNA-derived small RNAs (tsRNA) are a new type of noncoding RNAs that can be mainly classified into two groups: tRFs (tRNA-derived fragments) and tiRNAs (tRNA halves). The abnormal expression of tsRNAs is known to play an important role in the biological progression of breast cancer. However, it's still unclear about the mechanism of tsRNAs in cancer. tRF-1-Ser is a tRF that is high expression in breast cancer and negatively regulated by 25(OH)D. Our study aims to find out the effect of tRF-1-Ser on breast cancer and explore the change of RNA in tRF-1-Ser knock-down breast cancer cells.
2024-05-15 | GSE249937 | GEO