Project description:Metabolic adaptation refers to the regulation of cellular metabolism to prevent tissue dysfunction in response to different forms of stress. Heme, an iron-containing porphyrin, is indispensable for oxygen transport and for the activity of hemoproteins such as catalases. Cytotoxic “labile” heme is readily degraded by two distinct heme oxygenases (HO). The conditional deletion of Hmox-1, the gene encoding the inducible heme-degrading enzyme heme oxygenase (HO)-1, impairs metabolic adaptation to malaria and to polymicrobial infection. Embryonic deficiency in HO-1 is partially lethal in mice and surviving animals show progressive chronic inflammatory disease making them an unsuitable model to study metabolic adaptation. Here we found that mice with an inducible deletion of Hmox1 (Hmox1R26Δ/Δ) but not control mice rapidly succumbed to sterile hemolytic stress. Mortality was associated with heme-driven kidney failure, hypoglycemia, and disruption of adaptive thermoregulation. RNA sequencing and targeted metabolomics combined with data-driven in silico metabolic modeling revealed that failed renal metabolic adaptation is driven by altered oxidative phosphorylation and impaired pentose phosphate pathway. Heme-induced kidney failure and mortality in Hmox1R26Δ/Δ mice was not prevented with impairment of the inflammatory response, nor with antioxidants. Our results emphasize the critical importance of Hmox1 expression in hemolytic stress leading to acute kidney injury and death.
Project description:Here we quantitatively describe the influence of cell growth rate and amino acid metabolic context on gene expression in the eukaryal model organism Saccharomyces cerevisiae. We show that growth rate and metabolic cues regulate ~70% of the yeast transcriptome and proteome, thereby exerting gene expression control in a global manner. We find that the growth rate-dependent differential gene expression largely reflects changing availabilities of the mRNA and protein synthesis machineries, while metabolic cues influences gene expression through the availabilities of amino acids and nucleotides. Genes in central carbon metabolism, however, are regulated independently of these global physiological controls, demonstrating distinct mechanisms to control their expression levels.
Project description:Expression profiles of 110 the central metabolism-related enzymes were obtained by the selected reaction monitoring (SRM) assay methods using LC-MS/MS from the wild type (BY4742), a GCR2 gene deletion strain, and 29 single-gene deletion strains lacking enzyme genes responsible for central carbon metabolism (including CIT1, ENO1, FBP1, GCR2, GND1, GPD1, GPM2, HOR2, HXK1, HXK2, IDH1, IDH2, IDP1, LPD1, MAE1, MDH1, MDH2, PDA1, PDC1, PFK1, PYC2, RPE1, TAL1, TDH1, TDH2, TDH3, TKL1, TPS1, TPS2, and ZWF1 genes).
The central carbon metabolism is strictly controlled by modulation of enzyme expressions to maintain an essential system of living organisms. In this study, metabolic safety mechanisms in the model organism, Saccharomyces cerevisiae, were investigated by direct determination of enzyme expression levels. Targeted proteome analysis of 31 S. cerevisiae wild type and mutant strains revealed that at least 30% of the observed variations in enzyme expression levels could be explained by global regulatory mechanisms. Co-expression analysis revealed that expression levels of enzymes involved in trehalose metabolism and glycolysis changed in a coordinated manner under the control of the transcription factors for global regulation.