Project description:The number of tRNA isodecoders has increased dramatically in mammals, but the specific molecular and physiological reasons for this expansion remain elusive. To address this fundamental question we used CRISPR editing to knockout the seven-membered phenylalanine tRNA gene family in mice, both individually and combinatorially. Using ATAC-Seq, RNA-seq and proteomics we observed distinct molecular consequences of individual tRNA deletions. We show that tRNA-Phe-1-1 is required for neuronal function and its loss is partially compensated by increased expression of other tRNAs but results in mistranslation. In contrast, the other tRNA-Phe isodecoder genes buffer the loss of each of the remaining six tRNA-Phe genes. In the tRNA-Phe gene family, the expression of at least six tRNA-Phe alleles is required for embryonic viability and tRNA-Phe-1-1 is most important for development and survival. Our results reveal that the multi-copy configuration of tRNA genes is required to buffer translation and viability in mammals.
Project description:The number of tRNA isodecoders has increased dramatically in mammals, but the specific molecular and physiological reasons for this expansion remain elusive. To address this fundamental question we used CRISPR editing to knockout the seven-membered phenylalanine tRNA gene family in mice, both individually and combinatorially. Using ATAC-Seq, RNA-seq and proteomics we observed distinct molecular consequences of individual tRNA deletions. We show that tRNA-Phe-1-1 is required for neuronal function and its loss is partially compensated by increased expression of other tRNAs but results in mistranslation. In contrast, the other tRNA-Phe isodecoder genes buffer the loss of each of the remaining six tRNA-Phe genes. In the tRNA-Phe gene family, the expression of at least six tRNA-Phe alleles is required for embryonic viability and tRNA-Phe-1-1 is most important for development and survival. Our results reveal that the multi-copy configuration of tRNA genes is required to buffer translation and viability in mammals.
Project description:A previous study showed that a plasmid expressing IFNa (pIFNa) strongly enhanced protection and antibody production of a DNA vaccine against infectious salmon anemia virus (ISAV) in Atlantic salmon. The vaccine consisted of a plasmid (pHE) expressing the virus hemagglutinin-esterase as an antigen. To increase the understanding of the adjuvant effect of pIFNa, here compared transcriptome responses in salmon muscle at the injection site at week 1 and 2 after injection of pIFNa, pHE, plasmid control (pcDNA3.3) and PBS,respectively. A major was that both the control plasmid pcDNA3.3 and pHE caused responses similar to pIFNa, but at lower magnitude. Plasmid DNA may thus by itself have adjuvant activity as observed in mammalian models. Notably, pHE had a lower effect on many immune genes including ISGs and chemokines than pcDNA3.3, which suggested an inhibitory effect of the viral protein
Project description:Although organ hypofunction and immunosuppression are life-threatening features of severe sepsis, the hypofunctioning organs and immune cells usually regain normal functionality if patients survive. We tested the hypothesis that low extracellular pH (pHe) can induce reversible metabolic and functional changes in tissue macrophages. When compared with macrophages cultured at normal pHe, macrophages living in an acidic medium used less glucose and exogenous fatty acid to produce ATP. Lactate, glutamine, and de novo synthesized fatty acids supported ATP production by mitochondria that gained greater mass, maximal oxygen consumption rate, and spare respiratory capacity. The cells transitioned to a M2-like state, with altered immune responses to LPS and slightly decreased phagocytic ability, yet they regained basal energy production, normal mitochondrial function and pro-inflammatory responsiveness when neutral pHe was restored. Low pHe induces changes that support macrophage survival while rendering the cells less pro-inflammatory (more ‘tolerant’) and less able to phagocytose bacteria. Macrophage responses to low interstitial pH may contribute to the reversible organ hypofunction and immunoparalysis noted in many patients with sepsis.
Project description:N-lactoyl-phenylalanine (Lac-Phe) is a lactate-derived metabolite that suppresses food intake and body weight. Little is known about the mechanisms that mediate Lac-Phe transport across cell membranes. Here we identify SLC17A1 and SLC17A3, two kidney-restricted plasma membrane-localized solute carriers, as physiologic urine Lac-Phe transporters. In cell culture, SLC17A1/3 exhibit high Lac-Phe efflux activity. In humans, levels of Lac-Phe in urine exhibit a strong genetic association with the SLC17A1-4 locus. Urine Lac-Phe levels are also increased following a Wingate sprint test. In mice, genetic ablation of either SLC17A1 or SLC17A3 reduces urine Lac-Phe levels. Despite these differences, both knockout strains have normal blood Lac-Phe and body weights, demonstrating SLC17-dependent de-coupling of urine and plasma Lac-Phe pools. Together, these data establish SLC17A1/3 family members as the physiologic urine transporters for Lac-Phe and uncover a biochemical pathway for the renal excretion of this signaling metabolite. Our data do not exclude the involvement of other transporters in mediating Lac-Phe transport.
Project description:Suppressing spurious cryptic transcription by a repressive intragenic chromatin state featuring trimethylated lysine 36 on histone H3 (H3K36me3) and DNA methylation is critical for maintaining self-renewal capacity in mouse embryonic stem cells. In yeast and nematodes, such cryptic transcription is elevated with age, and reducing the levels of age-associated cryptic transcription extends yeast lifespan. Whether cryptic transcription is also increased during mammalian aging is unknown. We show for the first time an age-associated elevation in cryptic transcription in several stem cell populations, including murine hematopoietic stem cells (mHSCs) and neuronal stem cells (NSCs) and human mesenchymal stem cells (hMSCs). Using DECAP-seq, we mapped and quantified age-associated cryptic transcription in hMSCs aged in vitro. Regions with significant age-associated cryptic transcription have a unique chromatin signature: decreased H3K36me3 and increased H3K4me1, H3K4me3, and H3K27ac with age. Furthermore, genomic regions undergoing such age-dependent chromatin changes resemble known promoter sequences and are bound by the promoter-associated protein TBP even in young cells. Hence, the more permissive chromatin state at intragenic cryptic promoters likely underlies the increase of cryptic transcription in aged mammalian stem cells.
Project description:Sphingomonas wittichii RW1 is a bacterium isolated for its ability to degrade the toxic polyaromatic hydrocarbon dibenzofuran (dbf) and its polychlorinated derivatives. Its genome consists of a chromosome and two plasmids, encoding for more than 5300 genes. We studied genome-wide expression of strain RW1 to dbf in three different experimental setups, including both batch cultures and chemostats, comparing in all cases to the transcriptome of cells grown on phenylalanine as carbon source. A short exposure to DBF in chemostat or in batch, provoked the up-regulation of the ECF sigma 24, catalases, peroxiredoxins, chaperones, an aquaporin, several OmpA domain-containing proteins and the down-regulation of genes involved in TCA cycle, oxidative phosphorylation, amino acid metabolism and ribosomal proteins. When growing strain RW1 on DBF, genes known to be involved in DBF degradation were induced 2 to 4 fold. Additionally, two cluster of genes, putatively participating in the gentisate and meta-cleavage branches of the DBF degradation pathway, were induced from 12 to 19 fold. Three experiments are summarized here. 1. Compares the response of exponentially growing S.wittichii RW1 cells on phenylalanine (Phe), washed and resuspended in Phe for 30 min, with that of cells resuspended in DBF medium for 30 min (Phe1_shock, DBF1_schock, etc.). 2. Compares response of RW1 cells grown in batch medium with Phe or DBF as sole carbon and energy source, and harvested in exponential phase (Phe1_long, DBF1_long, etc. triplicates). 3. Comparison of transcriptome of RW1 cells grown continuously in chemostat on phenylalanine as carbon-limited substrate, with cells that have experienced instant exposure to phenylalanine plus DBF. This is done by pulsing DBF to maximum solubility and a simultaneous change in feed medium to Phe+ DBF. Samples before transition (Phe ctrl1-chem, etc. quadruplates), after 30 min (DBF 30m1-chem, etc), 1 h, 2 h and 6 h (DBF6h1-chem, etc.).