Project description:Maintaining metabolic homeostasis in response to fluctuating nutrient intake requires intricate coordination between tissues of multicellular animals. The insulin/glucagon axis is well known to hormonally coordinate organism-wide carbohydrate metabolism. The ChREBP/Mondo-Mlx transcription factors regulate glycolytic and lipogenic genes locally in hepatocytes and adipocytes, but its role in systemic metabolic homeostasis has remained poorly understood. We demonstrate that Mondo-Mlx controls gene activity in several peripheral tissues of Drosophila melanogaster, where it regulates nutrient digestion and transport as well as carbohydrate, amino acid and lipid metabolism. In addition to directly regulating metabolic genes Mondo-Mlx controls a regulatory network composed of the Activin ligand Dawdle and GLI similar transcription factor Sugarbabe. Dawdle and Sugarbabe contribute to the regulation of a subset of Mondo-Mlx-dependent processes, including sugar-induced de novo synthesis of serine and fatty acids. In summary, our study establishes Mondo-Mlx sugar sensor as a master regulator of organismal metabolic homeostasis upon sugar feeding.
Project description:Maintaining metabolic homeostasis in response to fluctuating nutrient intake requires intricate coordination between tissues of multicellular animals. The insulin/glucagon axis is well known to hormonally coordinate organism-wide carbohydrate metabolism. The ChREBP/Mondo-Mlx transcription factors regulate glycolytic and lipogenic genes locally in hepatocytes and adipocytes, but its role in systemic metabolic homeostasis has remained poorly understood. We demonstrate that Mondo-Mlx controls gene activity in several peripheral tissues of Drosophila melanogaster, where it regulates nutrient digestion and transport as well as carbohydrate, amino acid and lipid metabolism. In addition to directly regulating metabolic genes Mondo-Mlx controls a regulatory network composed of the Activin ligand Dawdle and GLI similar transcription factor Sugarbabe. Dawdle and Sugarbabe contribute to the regulation of a subset of Mondo-Mlx-dependent processes, including sugar-induced de novo synthesis of serine and fatty acids. In summary, our study establishes Mondo-Mlx sugar sensor as a master regulator of organismal metabolic homeostasis upon sugar feeding.
Project description:Raghunathan2010 - Genome-scale metabolic
network of Francisella tularensis (iRS605)
This model is described in the article:
Systems approach to
investigating host-pathogen interactions in infections with the
biothreat agent Francisella. Constraints-based model of
Francisella tularensis.
Raghunathan A, Shin S, Daefler
S.
BMC Syst Biol 2010; 4: 118
Abstract:
BACKGROUND: Francisella tularensis is a prototypic example
of a pathogen for which few experimental datasets exist, but
for which copious high-throughout data are becoming available
because of its re-emerging significance as biothreat agent. The
virulence of Francisella tularensis depends on its growth
capabilities within a defined environmental niche of the host
cell. RESULTS: We reconstructed the metabolism of Francisella
as a stoichiometric matrix. This systems biology approach
demonstrated that changes in carbohydrate utilization and amino
acid metabolism play a pivotal role in growth, acid resistance,
and energy homeostasis during infection with Francisella. We
also show how varying the expression of certain metabolic genes
in different environments efficiently controls the metabolic
capacity of F. tularensis. Selective gene-expression analysis
showed modulation of sugar catabolism by switching from
oxidative metabolism (TCA cycle) in the initial stages of
infection to fatty acid oxidation and gluconeogenesis later on.
Computational analysis with constraints derived from
experimental data revealed a limited set of metabolic genes
that are operational during infection. CONCLUSIONS: This
integrated systems approach provides an important tool to
understand the pathogenesis of an ill-characterized biothreat
agent and to identify potential novel drug targets when rapid
target identification is required should such microbes be
intentionally released or become epidemic.
This model is hosted on
BioModels Database
and identified by:
MODEL1507180003.
To cite BioModels Database, please use:
BioModels Database:
An enhanced, curated and annotated resource for published
quantitative kinetic models.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
CC0
Public Domain Dedication for more information.
Project description:Transcripts libraries were prepared from three sugarcane genotypes with high-sugar (HS), medium-sugar (MS) or low-sugar (LS) content that were treated with ethylene or H2O. The libraries were sequenced with the Illumina paired-end HiSeq platform.Transcriptomic analyses have identified about 160,000 unigenes of which 86000 annotated genes were classified into functional groups associated with carbohydrate metabolism, signaling, localization, transport, hydrolysis, growth, catalytic activity, membrane and storage, suggesting the structural and functional specification, including sucrose accumulation, occurring in maturing internodes. About 25,000 genes were differentially expressed between all genotypes and treatments combined. Genotype had a dominant effect on differential gene expression than ethylene treatment. Sucrose and starch metabolism genes were more responsive to ethylene treatment in low-sugar genotype. Ethylene caused differential gene expression of many stress-related transcription factors, carbohydrate metabolism, hormone metabolism and epigenetic modification. Ethylene-induced expression of ethylene-responsive transcription factors, cytosolic acid- and cell wall-bound invertases, and ATPase was more pronounced in low- than in high-sugar genotype, suggesting an ethylene-stimulated sink activity and consequent increased sucrose accumulation in low-sugar genotype.
Project description:Our transcriptome data shows that comparative transcriptomics analysis was performed on L. lactis WH101 and L. lactis NZ9000 to investigated the response mechanisms of microbial cells during acid stress. Carbohydrate metabolism and sugar transporters were strengthened to provide more energy. Amino acids metabolism and transporters were regulated to maintain intracellular pHi homeostasis and generate ATP. Fatty acid metabolism was also regulated to enhance the acid tolerance of cells. Moreover, transcriptional regulators and stress response proteins were also found to be related to acid stress.
Project description:The number, size, and composition of lipid droplets can be influenced by dietary changes that shift energy substrate availability. This diversification of lipid droplets can promote metabolic flexibility and shape cellular stress responses in unique tissues with distinctive metabolic roles. Using Drosophila, we uncovered a role for myocyte enhancer-factor 2 (MEF2) in modulating diet-dependent lipid droplet diversification within adult striated muscle, impacting mortality rates. Muscle-specific attenuation of MEF2, whose chronic activation maintains glucose and mitochondrial homeostasis, leads to the accumulation of large, cholesterol ester-enriched intramuscular lipid droplets in response to high calorie, carbohydrate sufficient diets. The diet-dependent accumulation of these lipid droplets also correlates with both enhanced stress protection in muscle and increases in organismal lifespan. Furthermore, MEF2 attenuation releases an antagonistic regulation of cell cycle gene expression programs, and up-regulation of Cyclin E is required for diet-and-MEF2 dependent diversification of intramuscular lipid droplets. The integration of MEF2-regulated gene expression networks with dietary responses thus plays a critical role in shaping muscle metabolism and function, further influencing organismal lifespan. Together, these results highlight a potential protective role for intramuscular lipid droplets during dietary adaptation.
Project description:Carbohydrate Responsive Element-Binding Protein (ChREBP) is a carbohydrate sensing transcription factor that regulates both adaptive and maladaptive genomic responses in coordination of systemic fuel homeostasis. Genetic variants in the ChREBP locus associate with diverse metabolic traits in humans, including circulating lipids. To identify novel ChREBP-regulated hepatokines that contribute to its systemic metabolic effects, we integrated ChREBP ChIP-seq analysis in mouse liver with human genetic and genomic data for lipid traits and identified Hepatocyte Growth Factor Activator (HGFAC) as a promising ChREBP-regulated candidate in mice and humans. HGFAC is a protease that activates the pleiotropic hormone Hepatocyte Growth Factor (HGF). We demonstrate that HGFAC KO mice have phenotypes concordant with putative loss-of-function variants in human HGFAC. Moreover, in gain- and loss-of-function genetic mouse models, we demonstrate that HGFAC enhances lipid and glucose homeostasis, which may be mediated in part through actions to activate hepatic PPARγ activity. Together, our studies show that ChREBP mediates an adaptive response to overnutrition via activation of HGFAC in the liver to preserve glucose and lipid homeostasis.
Project description:Carbohydrate Responsive Element-Binding Protein (ChREBP) is a carbohydrate sensing transcription factor that regulates both adaptive and maladaptive genomic responses in coordination of systemic fuel homeostasis. Genetic variants in the ChREBP locus associate with diverse metabolic traits in humans, including circulating lipids. To identify novel ChREBP-regulated hepatokines that contribute to its systemic metabolic effects, we integrated ChREBP ChIP-seq analysis in mouse liver with human genetic and genomic data for lipid traits and identified Hepatocyte Growth Factor Activator (HGFAC) as a promising ChREBP-regulated candidate in mice and humans. HGFAC is a protease that activates the pleiotropic hormone Hepatocyte Growth Factor (HGF). We demonstrate that HGFAC KO mice have phenotypes concordant with putative loss-of-function variants in human HGFAC. Moreover, in gain- and loss-of-function genetic mouse models, we demonstrate that HGFAC enhances lipid and glucose homeostasis, which may be mediated in part through actions to activate hepatic PPARγ activity. Together, our studies show that ChREBP mediates an adaptive response to overnutrition via activation of HGFAC in the liver to preserve glucose and lipid homeostasis.