A tRNA modification balances carbon and nitrogen metabolism by regulating phosphate homeostasis, to couple metabolism to cell cycle progression.
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ABSTRACT: A tRNA modification balances carbon and nitrogen metabolism by regulating phosphate homeostasis, to couple metabolism to cell cycle progression.
Project description:Cells must appropriately sense and integrate multiple metabolic resources to commit to proliferation. Here, we report that cells regulate nitrogen (amino acid) and carbon metabolic homeostasis through tRNA U34-thiolation. Despite amino acid sufficiency, tRNA-thiolation deficient cells appear amino acid starved. In these cells, carbon flux towards nucleotide synthesis decreases, and trehalose synthesis increases, resulting in metabolic a starvation-signature. Thiolation mutants have only minor translation defects. However, these cells exhibit strongly decreased expression of phosphate homeostasis genes, mimicking a phosphate-limited state. Reduced phosphate enforces a metabolic switch, where glucose-6-phosphate is routed towards storage carbohydrates. Notably, trehalose synthesis, which releases phosphate and thereby restores phosphate availability, is central to this metabolic rewiring. Thus, cells use thiolated tRNAs to perceive amino acid sufficiency, and balance amino acid and carbon metabolic flux to maintain metabolic homeostasis, by controlling phosphate availability. These results further biochemical explain how phosphate availability determines a switch to a ‘starvation-state’.
Project description:Cells must appropriately sense and integrate multiple metabolic resources to commit to proliferation. Here, we report that S. cerevisiae cells regulate carbon and nitrogen metabolic homeostasis through tRNA U34-thiolation. Despite amino acid sufficiency, tRNA-thiolation deficient cells appear amino acid starved. In these cells, carbon flux towards nucleotide synthesis decreases, and trehalose synthesis increases, resulting in a starvation-like metabolic signature. Thiolation mutants have only minor translation defects. However, in these cells phosphate homeostasis genes are strongly down-regulated, resulting in an effectively phosphate-limited state. Reduced phosphate enforces a metabolic switch, where glucose-6-phosphate is routed towards storage carbohydrates. Notably, trehalose synthesis, which releases phosphate and thereby restores phosphate availability, is central to this metabolic rewiring. Thus, cells use thiolated tRNAs to perceive amino acid sufficiency, balance carbon and amino acid metabolic flux and grow optimally, by controlling phosphate availability. These results further biochemically explain how phosphate availability determines a switch to a 'starvation-state'.
Project description:Here, gene profiles in rat spermatogonial stem cell lines are compared to publicly available mouse, monkey and human spermatogonial gene profiles. Interestingly, rat spermatogonia expressed metabolic control factors Foxa1, Foxa2 and Foxa3. Germline Foxa2 was enriched in Gfra1Hi and Gfra1Low undifferentiated A-single spermatogonia. Foxa2-bound loci in spermatogonial chromatin were over-represented by conserved stemness genes (Dusp6, Gfra1, Etv5, Rest, Nanos2, Foxp1) that intersect bioinformatically with conserved glutathione/pentose phosphate metabolism genes (Tkt, Gss, Gclc, Gclm, Gpx1, Gpx4, Fth), marking elevated spermatogonial GSH:GSSG. Cystine-uptake and intracellular conversion to cysteine typically couple glutathione biosynthesis to pentose phosphate metabolism. Rat spermatogonia, curiously, displayed poor germline stem cell viability in cystine-containing media, and, like primate spermatogonia, exhibited reduced transsulfuration pathway markers. Exogenous cysteine, cysteine-like mercaptans, somatic testis cells and ferroptosis inhibitors counteracted the cysteine starvation-induced spermatogonial death and stimulated spermatogonial growth factor activity in vitro.
Project description:In Aspergillus nidulans, nitrogen and carbon metabolism are under the control of wide-domain regulatory systems, including nitrogen metabolite repression, carbon catabolite repression. Transcriptomic analysis of the wild type strain grown under different combinations of carbon and nitrogen regimes was performed, to identify differentially regulated genes. Carbon metabolism predominates as the most important regulatory signal but for many genes, both carbon and nitrogen metabolisms coordinate regulation.
Project description:This SuperSeries is composed of the following subset Series: GSE39746: Argonaute proteins couple chromatin silencing to alternative splicing (exon array) GSE39748: Argonaute proteins couple chromatin silencing to alternative splicing (RNA IP-Seq) Refer to individual Series
Project description:Bacterial small RNAs (sRNAs) are well known to modulate gene expression by base pairing with trans-encoded transcripts and are typically non-coding. However, several sRNAs have been reported to also contain an open reading frame and thus are considered dual-function RNAs. In this study, we discovered a dual-function RNA from Vibrio cholerae, called VcdRP, harboring a 29 amino acid small protein (VcdP), as well as a base-pairing sequence. Using a forward genetic screen, we identified VcdRP as a repressor of cholera toxin production and link this phenotype to the inhibition of carbon transport by the base-pairing segment of the regulator. By contrast, we demonstrate that the VcdP small protein acts downstream of carbon transport by binding to citrate synthase (GltA), the first enzyme of the citric acid cycle. Interaction of VcdP with GltA results in increased enzyme activity and together VcdR and VcdP reroute carbon metabolism. We further show that transcription of vcdRP is repressed by CRP allowing us to provide a model in which VcdRP employs two different molecular mechanisms to synchronize central metabolism in V. cholerae.