Effects of tRNA[Ser]Sec anticodon stem loop modifications on selenoprotein expression
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PROVIDER: PRJNA762342 | ENA |
REPOSITORIES: ENA
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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:Comparative analysis of gene expression in bone marrow-derived macrophages (BMDM) from trsp knockout mice (Trspfl/fl-LysM-Cre+/-) and Control (Trspfl/fl-LysM-Cre-/-) mice. Selenium, a micronutrient whose deficiency in the diet causes immune dysfunction and inflammatory disorders, exerts its physiological effects partly in the form of selenium-containing proteins (selenoproteins). Incorporation of selenium into the amino acid selenocysteine (Sec), and subsequently into selenoproteins, is mediated by Sec tRNA[Ser]Sec. To identify macrophage-specific selenoprotein function, we generated mice with the Sec tRNA[Ser]Sec gene specifically deleted in myeloid cells. These mutant mice were devoid of the selenoproteome in macrophages, yet exhibited largely normal inflammatory responses. However, selenoprotein deficiency led to aberrant expression of extracellular matrix-related genes, and diminished migration of macrophages in a protein gel matrix. Therefore, selenium status may affect immune defense and tissue homeostasis through its effect on selenoprotein expression and the trafficking of tissue macrophages.
2009-12-22 | GSE15610 | GEO
Project description:Comparative analysis of gene expression in bone marrow-derived macrophages (BMDM) from trsp knockout mice (Trspfl/fl-LysM-Cre+/-) and Control (Trspfl/fl-LysM-Cre-/-) mice. Selenium, a micronutrient whose deficiency in the diet causes immune dysfunction and inflammatory disorders, exerts its physiological effects partly in the form of selenium-containing proteins (selenoproteins). Incorporation of selenium into the amino acid selenocysteine (Sec), and subsequently into selenoproteins, is mediated by Sec tRNA[Ser]Sec. To identify macrophage-specific selenoprotein function, we generated mice with the Sec tRNA[Ser]Sec gene specifically deleted in myeloid cells. These mutant mice were devoid of the selenoproteome in macrophages, yet exhibited largely normal inflammatory responses. However, selenoprotein deficiency led to aberrant expression of extracellular matrix-related genes, and diminished migration of macrophages in a protein gel matrix. Therefore, selenium status may affect immune defense and tissue homeostasis through its effect on selenoprotein expression and the trafficking of tissue macrophages. We have generated mice in which we have selectively removed the selenocysteine tRNA gene (trsp) in macrophages under the control of LysM-Cre promoter. Microarray analysis was performed on RNA samples taken from bone marrow-derived macrophages in knockout and control mice. 1. Control unstimulated 2. Knockout unstimulated 3. Control lipopolysaccharide (LPS) stimulated (4h) 4. Knockout LPS stimulated (4h). Three replicates for each condition. Thus, a total of 12 samples.
2009-12-21 | E-GEOD-15610 | biostudies-arrayexpress
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:Selenoproteins are a small family of proteins containing the trace element selenium in form of the rare amino acid selenocysteine (Sec), which is decoded by the UGA codon. In humans, a number of pathogenic mutations in genes encoding distinct selenoproteins or selenoprotein biosynthesis factors have been identified. Pathogenic mutations in selenocysteine synthase (SEPSECS), which catalyzes the last step in Sec-tRNA[Ser]Sec biosynthesis, were reported in children suffering from progressive cerebello-cerebral atrophy. To understand the underlying mechanisms of SEPSECS mutations, we generated a novel mouse model recapitulating the respective human pathogenic Y334C mutation in the murine Sepsecs gene (SepsecsY334C). Unlike in patients, homozygous mutant pups died perinatally with signs of cardio-respiratory failure. Perinatal death is reminiscent of the Sedaghatian spondylometaphyseal dysplasia disorder in humans, which is caused by inactivating mutations of the gene encoding the selenoprotein and key ferroptosis regulator glutathione peroxidase 4 (GPX4). Protein expression levels of distinct selenoproteins in SepsecsY334C/Y334C mice were found to be generally reduced in brain and isolated cortical neurons, while transcriptomics analysis uncovered an upregulation of NRF2-regulated genes. Crossbreeding of SepsecsY334C/Y334C mice with mice harboring a targeted mutation of the catalytically active site Sec to Cys in GPX4 surprisingly rescued perinatal death of SepsecsY334C/Y334C mice, showing that the cardio-respiratory defects of Sepsecs-mutant mice were caused by the lack of GPX4. Like in SepsecsY334C/Y334C mice, selenoprotein expression levels remained low and NRF2-regulated genes remained highly expressed in these compound mutant mice, indicating that selenium-independent GPX4, along with a sustained antioxidant response are sufficient to compensate for dysfunctional Sec-tRNA[Ser]Sec biosynthesis. Our findings imply that children with mutations in SEPSECS or GPX4 may benefit from treatments partially compensating for impaired GPX4 activity.
2021-11-24 | GSE181852 | GEO
Project description:Diverse chemical modifications fine-tune the function and metabolism of tRNA. Although tRNA modification is universal in all kingdoms of life, profiles of modifications, their functions, and physiological roles have not been elucidated in most organisms including the human pathogen, Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis. To identify physiologically important modifications, we surveyed the tRNA of Mtb, using tRNA sequencing (tRNA-seq). Reverse transcription-derived error signatures in tRNA-seq predicted the sites and presence of 9 modifications. Several chemical treatments prior to tRNA-seq expanded the number of predictable modifications. Deletion of Mtb genes encoding two modifying enzymes, TruB and MnmA, eliminated their respective tRNA modifications, validating the presence of modified sites in tRNA species.
2023-08-11 | GSE240200 | GEO
Project description:tRNAs are heavily decorated with post-transcriptional modifications (tRNA modifications). Profile of tRNA modifications in non-model organisms are largely uncharacterized. Here using high-throughput sequencing, sites and frequency of tRNA modifications are predicted in Vibrio cholerae and Escherichia coli. During cDNA synthesis, some modifications cause misincorporation of a wrong base or termination of reverse transcription (RT). Using these RT-derived signatures we aim to explore organism-specific modifications and to track changes in modification frequency among different cellular conditions.
2020-05-15 | GSE147614 | GEO
Project description:The function of intragenic tRNA R-loop
| PRJNA640382 | ENA
Project description:Previously, combined loss of specific anticodon loop modifications was shown to impair the function of distinct tRNAs in Saccharomyces cerevisiae. Surprisingly, each scenario resulted in shared cellular phenotypes, the basis of which is unclear. To investigate how loss of different tRNA modifications can induce overlapping phenotypes, we characterized global transcription patterns of modification mutants with defects in either tRNAGlnUUG or tRNALysUUU function. We observe that the mutants share an inappropriate induction of multiple starvation responses, including derepression of glucose and nitrogen catabolite-repressed genes as well as improper activation of amino acid biosynthesis and autophagy genes, all of which occur prematurely and inadequately in exponential growth phase. We further demonstrate that improper responses to starvation as well as the propensity of the tRNA modification mutants to form protein aggregates are diminished upon overexpression of tRNAGlnUUG or tRNALysUUU, the tRNA species that lack the modifications of interest. Hence, our data suggest that global alterations in mRNA translation and proteostasis (rather than codon specific defects in translation) account for the transcriptional stress signatures that are commonly triggered by loss of anticodon modifications in different tRNAs.
2020-04-01 | GSE141887 | GEO