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BCAT1 affects mitochondrial metabolism independently of leucine transamination in activated human macrophages.

ABSTRACT: In response to environmental stimuli, macrophages change their nutrient consumption and undergo an early metabolic adaptation that progressively shapes their polarization state. During the transient, early phase of pro-inflammatory macrophage activation, an increase in tricarboxylic acid (TCA) cycle activity has been reported, but the relative contribution of branched-chain amino acid (BCAA) leucine remains to be determined. Here, we show that glucose but not glutamine is a major contributor of the increase in TCA cycle metabolites during early macrophage activation in humans. We then show that, although uptake of BCAAs is not altered, their transamination by BCAT1 is increased following 8 h lipopolysaccharide (LPS) stimulation. Of note, leucine is not metabolized to integrate into the TCA cycle in basal or stimulated human macrophages. Surprisingly, the pharmacological inhibition of BCAT1 reduced glucose-derived itaconate, α-ketoglutarate and 2-hydroxyglutarate levels without affecting succinate and citrate levels, indicating a partial inhibition of the TCA cycle. This indirect effect is associated with NRF2 (also known as NFE2L2) activation and anti-oxidant responses. These results suggest a moonlighting role of BCAT1 through redox-mediated control of mitochondrial function during early macrophage activation.

SUBMITTER: Ko JH

PROVIDER: S-EPMC7116427 | biostudies-literature |

REPOSITORIES: biostudies-literature

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BCAT1 controls metabolic reprogramming in activated human macrophages and is associated with inflammatory diseases.

Project description:Branched-chain aminotransferases (BCAT) are enzymes that initiate the catabolism of branched-chain amino acids (BCAA), such as leucine, thereby providing macromolecule precursors; however, the function of BCATs in macrophages is unknown. Here we show that BCAT1 is the predominant BCAT isoform in human primary macrophages. We identify ERG240 as a leucine analogue that blocks BCAT1 activity. Selective inhibition of BCAT1 activity results in decreased oxygen consumption and glycolysis. This decrease is associated with reduced IRG1 levels and itaconate synthesis, suggesting involvement of BCAA catabolism through the IRG1/itaconate axis within the tricarboxylic acid cycle in activated macrophages. ERG240 suppresses production of IRG1 and itaconate in mice and contributes to a less proinflammatory transcriptome signature. Oral administration of ERG240 reduces the severity of collagen-induced arthritis in mice and crescentic glomerulonephritis in rats, in part by decreasing macrophage infiltration. These results establish a regulatory role for BCAT1 in macrophage function with therapeutic implications for inflammatory conditions.

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Histone methyltransferase activity affects metabolism in human cells independently of transcriptional regulation.

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Activated macrophages control human adipocyte mitochondrial bioenergetics via secreted factors.

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| S-EPMC5641636 | biostudies-literature

Transamination is required for {alpha}-ketoisocaproate but not leucine to stimulate insulin secretion.

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| S-EPMC2962470 | biostudies-literature

IL17A Depletion Affects the Metabolism of Macrophages Treated with Gemcitabine.

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| S-EPMC7999796 | biostudies-literature

Leucine metabolism regulates TRI6 expression and affects deoxynivalenol production and virulence in Fusarium graminearum

Project description:TRI6 is a positive regulator of the trichothecene gene cluster and the production of trichothecene mycotoxins (deoxynivalenol [DON] and acetylated forms such as 15-ADON) in the cereal pathogen F. graminearum. As a global transcriptional regulator, TRI6 expression is modulated by nitrogen-limiting conditions, sources of nitrogen and carbon, pH, and light. However, the mechanism by which these diverse environmental factors affect TRI6 expression remains under-explored. In our effort to understand how nutrients affect TRI6 regulation, comparative digital expression profiling was performed with a wildtype F. graminearum and a Δtri6 mutant strain, grown in nutrient-rich conditions. Analysis showed that TRI6 negatively regulates genes of the branched-chain amino acid (BCAA) metabolic pathway. Feeding studies with deletion mutants of MCC, encoding methylcrotonyl-CoA-carboxylase, one of the key enzymes of leucine metabolism, showed that addition of leucine specifically down regulated TRI6 expression and reduced 15-ADON accumulation. Constitutive expression of TRI6 in the Δmcc mutant strain restored 15-ADON production. A combination of cellophane breach assays and pathogenicity experiments on wheat demonstrated that disrupting the leucine metabolic pathway significantly reduced disease. These findings suggest a complex interaction between one of the primary metabolic pathways with a global regulator of mycotoxin biosynthesis and virulence in F. graminearum. Triplicate samples of digital gene expression profiling data for the Tri6 mutant and wildtype strains were compared. **Please note that the raw data files for the current study are no longer available, and therefore are not included in the submission.

2015-08-01 | E-GEOD-71604 | biostudies-arrayexpress

Leucine metabolism regulates TRI6 expression and affects deoxynivalenol production and virulence in Fusarium graminearum

2015-08-01 | GSE71604 | GEO

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Exploiting cell metabolism for biocatalytic whole-cell transamination by recombinant Saccharomyces cerevisiae.

Project description:The potential of Saccharomyces cerevisiae for biocatalytic whole-cell transamination was investigated using the kinetic resolution of racemic 1-phenylethylamine (1-PEA) to (R)-1-PEA as a model reaction. As native yeast do not possess any ?-transaminase activity for the reaction, a recombinant yeast biocatalyst was constructed by overexpressing the gene coding for vanillin aminotransferase from Capsicum chinense. The yeast-based biocatalyst could use glucose as the sole co-substrate for the supply of amine acceptor via cell metabolism. In addition, the biocatalyst was functional without addition of the co-factor pyridoxal-5'-phosphate (PLP), which can be explained by a high inherent cellular capacity to sustain PLP-dependent reactions in living cells. In contrast, external PLP supplementation was required when cell viability was low, as it was the case when using pyruvate as a co-substrate. Overall, the results indicate a potential for engineered S. cerevisiae as a biocatalyst for whole-cell transamination and with glucose as the only co-substrate for the supply of amine acceptor and PLP.

| S-EPMC4253539 | biostudies-literature

Phosphatidylserine metabolism affects mitochondrial homeostasis in Drosophila

Project description:In Drosophila, insufficient biosynthesis of phosphatidylserine induced significant mitochondrial defects.Proteomic analysis of samples from drosophila salivary glands, we compared three genotypes, ppl-gal4 drived RNAi against w, pss and pss plus bbc.

2023-10-23 | PXD046310 |

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