Project description:Exposure to hypoxia disrupts energy metabolism and induces inflammation. However, the pathways and mechanisms underlying energy metabolism disorders caused by hypoxic conditions remain unclear. In this study, we constructed a hypoxic animal model and applied transcriptomic and non-targeted metabolomics techniques to further investigate the pathways and mechanisms of hypoxia exposure that disrupt energy metabolism. Transcriptome results showed that 3007 genes were significantly differentially expressed under hypoxic exposure, and Gene Ontology (GO) annotation analysis and Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analysis showed that the differentially expressed genes (DEGs) were mainly involved in energy metabolism and were significantly enriched in the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) pathway. Differential genes in the TCA cycle (IDH3A, SUCLA2, and MDH2) and OXPHOS pathway (NDUFA3, NDUFS7, UQCRC1, CYC1, and UQCRFS1) were validated using mRNA and protein expression, and the results showed downregulation. The results of non-targeted metabolomics showed that 365 significant differential metabolites were identified under plateau hypoxia stress. KEGG enrichment analysis showed that the differential metabolites were mainly enriched in metabolic processes, such as energy metabolism, nucleotide metabolism, and amino acid metabolism. Hypoxia exposure disrupted the TCA cycle and reduced the synthesis of amino acids and nucleotides by decreasing the concentrations of cis-aconitate, α-ketoglutarate, NADH, NADPH, most amino acids, purines, and pyrimidines. Bioinformatics analysis was used to identify inflammatory genes related to hypoxia exposure, and some inflammatory genes were selected for verification. We found that the mRNA and protein expression levels of IL1B, IL12B, S100A8, and S100A9 in kidney tissues were upregulated under hypoxic exposure. Our results suggest that hypoxia exposure inhibits the TCA cycle and OXPHOS signalling pathway by inhibiting IDH3A, SUCLA2, MDH2, NDUFFA3, NDUFS7, UQCRC1, CYC1, and UQCRFS1, thereby suppressing energy metabolism, inducing amino acid and nucleotide deficiency, and promoting inflammation, ultimately leading to kidney damage.
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:We analyzed the effects of enarodustat (JTZ-951; HIF stabilizer) on renal energy metabolism in streptozotocin-induced diabetic rat model. Transcriptome analysis of renal cortex revealed that genes related to fatty acid metabolism and amino acid metabolism were upregulated in diabetes and downregulated by enarodustat, whereas genes related to glucose metabolism were upregulated by enarodustat. Thus, HIF stabilization counteracts the renal energy metabolism alterations occurring in the early stages of diabetic kidney disease.
Project description:Multinucleated giant cells (MGCs) are implicated in many diseases including schistosomiasis, sarcoidosis and arthritis. Formation of MGCs is energy intensive to enforce membrane fusion and cytoplasmic expansion. Here we used receptor activator of nuclear factor kappa-Β ligand (RANKL) induced osteoclastogenesis to model MGC formation. We found amino acid (AA) scarcity controls MGC formation and reveal specific requirements for extracellular arginine in RANKL cellular programming. Indeed, systemic arginine restriction improved outcome in multiple murine arthritis models, by inducing preosteoclast metabolic quiescence, associated with a dysregulated tricarboxylic acid (TCA) cycle, and diverted metabolic fluxes from central metabolic pathways independent of mTORC1 activity or global transcriptional and translational inhibition. A conserved metabolic mechanism occurred in IL-4 induced MGCs. Strikingly, we demonstrate that restriction of multiple AAs triggered metabolic adaptation and blocked MGC formation and each was rescued by their downstream metabolites. These data establish how environmental nutrients control the metabolic fate of polykaryons and suggest metabolic ways to manipulate MGC-associated pathologies and bone remodeling.
Project description:We analyzed the effects of enarodustat (JTZ-951; HIF stabilizer) on renal energy metabolism in alloxan-induced diabetic mouse model. Transcriptome analysis of renal tissue revealed that genes related to fatty acid metabolism were upregulated in diabetes, whereas genes related to glucose metabolism were upregulated by enarodustat. In addition, genes related to amino acid metabolism were upregulated by diabetes and downregulated by enarodustat. Thus, HIF stabilization counteracts the renal energy metabolism alterations occurring in the early stages of diabetic kidney disease.
Project description:We transcriptional profiled four transcription factor knockout strains in S288C background growing in YNB media + 2% glucose to understand the link between mRNA levels and our measured C13 fluxes of amino acid biosynthesis. We conducted this analysis as a follow up to our work on the Gcn4p transcription factor. Keywords: genetic modification
Project description:Glutamine is a key nutrient for tumor cells that supports nucleotide and amino acid biosynthesis, replenishes the TCA cycle intermediates and contributes to redox metabolism. We identified oncogenic KRAS as a critical regulator of the response to glutamine deprivation in NSCLC. Full activation of the ATF4 stress response pathway is dependent on expression of NRF2 downstream of oncogenic KRAS in NSCLC. Through this mechanism, KRAS alters amino acid uptake and metabolism and sustains mTORC1 signaling during nutrient stress. Furthermore, we identified regulation of asparagine synthetase (ASNS) as a key effect of oncogenic KRAS signaling via ATF4 during glutamine deprivation, and a potential therapeutic target in KRAS mutant NSCLC.