scholarly journals β-Hydroxybutyrate Oxidation Promotes the Accumulation of Immunometabolites in Activated Microglia Cells

Metabolites ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 346
Author(s):  
Adrian Benito ◽  
Nabil Hajji ◽  
Kevin O’Neill ◽  
Hector C. Keun ◽  
Nelofer Syed
Keyword(s):  
Metabolic Regulation ◽  
Marker Gene ◽  
Tca Cycle ◽  
Metabolic Reprogramming ◽  
Glycolytic Flux ◽  
Dihydroxyacetone Phosphate ◽  
Glycolytic Intermediate ◽  
Critical Set ◽  
The Tca Cycle ◽  
Bv2 Cells

Metabolic regulation of immune cells has arisen as a critical set of processes required for appropriate response to immunological signals. While our knowledge in this area has rapidly expanded in leukocytes, much less is known about the metabolic regulation of brain-resident microglia. In particular, the role of alternative nutrients to glucose remains poorly understood. Here, we use stable-isotope (13C) tracing strategies and metabolomics to characterize the oxidative metabolism of β-hydroxybutyrate (BHB) in human (HMC3) and murine (BV2) microglia cells and the interplay with glucose in resting and LPS-activated BV2 cells. We found that BHB is imported and oxidised in the TCA cycle in both cell lines with a subsequent increase in the cytosolic NADH:NAD+ ratio. In BV2 cells, stimulation with LPS upregulated the glycolytic flux, increased the cytosolic NADH:NAD+ ratio and promoted the accumulation of the glycolytic intermediate dihydroxyacetone phosphate (DHAP). The addition of BHB enhanced LPS-induced accumulation of DHAP and promoted glucose-derived lactate export. BHB also synergistically increased LPS-induced accumulation of succinate and other key immunometabolites, such as α-ketoglutarate and fumarate generated by the TCA cycle. Finally, BHB upregulated the expression of a key pro-inflammatory (M1 polarisation) marker gene, NOS2, in BV2 cells activated with LPS. In conclusion, we identify BHB as a potentially immunomodulatory metabolic substrate for microglia that promotes metabolic reprogramming during pro-inflammatory response.

scholarly journals Metabolic Constants and Plasticity of Cancer Cells in a Limiting Glucose and Glutamine Microenvironment—A Pyruvate Perspective

2020 ◽  
Vol 10 ◽  
Author(s):  
Angela M. Otto
Keyword(s):  
Cancer Cells ◽  
Metabolic Network ◽  
Metabolic Pathways ◽  
Cancer Cell Line ◽  
Tca Cycle ◽  
Reaction Rates ◽  
Diagnostic Methods ◽  
Metabolic Reprogramming ◽  
Amino Acid Synthesis ◽  
The Tca Cycle

The metabolism of cancer cells is an issue of dealing with fluctuating and limiting levels of nutrients in a precarious microenvironment to ensure their vitality and propagation. Glucose and glutamine are central metabolites for catabolic and anabolic metabolism, which is in the limelight of numerous diagnostic methods and therapeutic targeting. Understanding tumor metabolism in conditions of nutrient depletion is important for such applications and for interpreting the readouts. To exemplify the metabolic network of tumor cells in a model system, the fate 13C6-glucose was tracked in a breast cancer cell line growing in variable low glucose/low glutamine conditions. 13C-glucose-derived metabolites allowed to deduce the engagement of metabolic pathways, namely glycolysis, the TCA-cycle including glutamine and pyruvate anaplerosis, amino acid synthesis (serine, glycine, aspartate, glutamate), gluconeogenesis, and pyruvate replenishment. While the metabolic program did not change, limiting glucose and glutamine supply reduced cellular metabolite levels and enhanced pyruvate recycling as well as pyruvate carboxylation for entry into the TCA-cycle. Otherwise, the same metabolic pathways, including gluconeogenesis, were similarly engaged with physiologically saturating as with limiting glucose and glutamine. Therefore, the metabolic plasticity in precarious nutritional microenvironment does not require metabolic reprogramming, but is based on dynamic changes in metabolite quantity, reaction rates, and directions of the existing metabolic network.

Protein hyperacylation links mitochondrial dysfunction with nuclear organization

2020 ◽  
Author(s):  
John Smestad ◽  
Micah McCauley ◽  
Matthew Amato ◽  
Yuning Xiong ◽  
Juan Liu ◽  
...  
Keyword(s):  
Chromatin Structure ◽  
Metabolic Regulation ◽  
Tca Cycle ◽  
Interphase Chromatin ◽  
Histone Octamer ◽  
The Tca Cycle ◽  
Transport Chain ◽  
Topologically Associated Domains ◽  
Biophysical Effects ◽  
Liquid Liquid Phase Separation

SummaryCellular metabolism is linked to epigenetics, but the biophysical effects of metabolism on chromatin structure and implications for gene regulation remain largely unknown. Here, using a broken tricarboxylic acid (TCA) cycle and disrupted electron transport chain (ETC) exemplified by succinate dehydrogenase subunit C (SDHC) deficiency, we investigated the effects of metabolism on chromatin architecture over multiple distance scales [nucleosomes (∼102 bp), topologically-associated domains (TADs; ∼105 – 106 bp), and chromatin compartments (106 – 108 bp)]. Metabolically-driven hyperacylation of histones led to weakened nucleosome positioning in multiple types of chromatin, and we further demonstrate that lysine acylation directly destabilizes histone octamer-DNA interactions. Hyperacylation of cohesin subunits correlated with decreased mobility on interphase chromatin and increased TAD boundary strength, suggesting that cohesin is metabolically regulated. Erosion of chromatin compartment distinctions reveals metabolic regulation of chromatin liquid-liquid phase separation. The TCA cycle and ETC thus modulate chromatin structure over multiple distance scales.

scholarly journals Non-conserved metabolic regulation by LKB1 distinguishes human and mouse lung adenocarcinoma

2021 ◽  
Author(s):  
Benjamin D Stein ◽  
John R Ferrarone ◽  
Eric E Gardner ◽  
Jae Won Chang ◽  
David Wu ◽  
...  
Keyword(s):  
Lung Adenocarcinoma ◽  
Metabolic Regulation ◽  
Triosephosphate Isomerase ◽  
Genetically Engineered ◽  
Metabolic Reprogramming ◽  
Mouse Lung ◽  
Glycolytic Flux ◽  
Evolutionary Divergence ◽  
Dependent Manner ◽  
Loss Of Function

KRAS is the most frequently mutated oncogene in human lung adenocarcinomas (hLUAD) and activating mutations in KRAS frequently co-occur with loss-of-function mutations in the tumor suppressor genes, TP53 or STK11/LKB1. However, mutation of all three genes is rarely observed in hLUAD, even though engineered mutations of all three genes produces a highly aggressive lung adenocarcinoma in mice (mLUAD). Here we provide an explanation of this difference between hLUAD and mLUAD by uncovering an evolutionary divergence in regulation of the glycolytic enzyme triosephosphate isomerase (TPI1). Using KRAS/TP53 mutant hLUAD cell lines, we show that TPI1 enzymatic activity can be altered via phosphorylation at Ser21 by the Salt Inducible Kinases (SIKs) in an LKB1-dependent manner; this allows modulation of glycolytic flux between completion of glycolysis and production of glycerol lipids. This metabolic flexibility appears to be critical in rapidly growing cells with KRAS and TP53 mutations, explaining why loss of LKB1 creates a metabolic liability in these tumors. In mice, the amino acid at position 21 of TPI1 is a Cys residue which can be oxidized to alter TPI1 activity, allowing regulation of glycolytic flux balance without a need for SIK kinases or LKB1. Our findings reveal an unexpected role for TPI1 in metabolic reprogramming and suggest that LKB1 and SIK family kinases are potential targets for treating KRAS/TP53 mutant hLUAD. Our data also provide a cautionary example of the limits of genetically engineered murine models as tools to study human diseases such as cancers.

scholarly journals Mycobacterium tuberculosis induces decelerated bioenergetic metabolism in human macrophages

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Bridgette M Cumming ◽  
Kelvin W Addicott ◽  
John H Adamson ◽  
Adrie JC Steyn
Keyword(s):  
Fatty Acids ◽  
Mycobacterium Tuberculosis ◽  
Human Monocyte ◽  
Tca Cycle ◽  
Metabolic Reprogramming ◽  
Flux Analysis ◽  
Human Macrophages ◽  
Extracellular Flux ◽  
The Tca Cycle ◽  
Bioenergetic Metabolism

How Mycobacterium tuberculosis (Mtb) rewires macrophage energy metabolism to facilitate survival is poorly characterized. Here, we used extracellular flux analysis to simultaneously measure the rates of glycolysis and respiration in real time. Mtb infection induced a quiescent energy phenotype in human monocyte-derived macrophages and decelerated flux through glycolysis and the TCA cycle. In contrast, infection with the vaccine strain, M. bovis BCG, or dead Mtb induced glycolytic phenotypes with greater flux. Furthermore, Mtb reduced the mitochondrial dependency on glucose and increased the mitochondrial dependency on fatty acids, shifting this dependency from endogenous fatty acids in uninfected cells to exogenous fatty acids in infected macrophages. We demonstrate how quantifiable bioenergetic parameters of the host can be used to accurately measure and track disease, which will enable rapid quantifiable assessment of drug and vaccine efficacy. Our findings uncover new paradigms for understanding the bioenergetic basis of host metabolic reprogramming by Mtb.

scholarly journals Highly flexible metabolism of the marine euglenozoan protist Diplonema papillatum

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Ingrid Škodová-Sveráková ◽  
Kristína Záhonová ◽  
Valéria Juricová ◽  
Maksym Danchenko ◽  
Martin Moos ◽  
...  
Keyword(s):  
Tca Cycle ◽  
Primary Energy ◽  
Pentose Phosphate ◽  
Metabolic Reprogramming ◽  
Metabolic Flexibility ◽  
Low Oxygen ◽  
Ecological Functions ◽  
Carbon Availability ◽  
The Tca Cycle ◽  
Transcriptomic Level

Abstract Background The phylum Euglenozoa is a group of flagellated protists comprising the diplonemids, euglenids, symbiontids, and kinetoplastids. The diplonemids are highly abundant and speciose, and recent tools have rendered the best studied representative, Diplonema papillatum, genetically tractable. However, despite the high diversity of diplonemids, their lifestyles, ecological functions, and even primary energy source are mostly unknown. Results We designed a metabolic map of D. papillatum cellular bioenergetic pathways based on the alterations of transcriptomic, proteomic, and metabolomic profiles obtained from cells grown under different conditions. Comparative analysis in the nutrient-rich and nutrient-poor media, as well as the absence and presence of oxygen, revealed its capacity for extensive metabolic reprogramming that occurs predominantly on the proteomic rather than the transcriptomic level. D. papillatum is equipped with fundamental metabolic routes such as glycolysis, gluconeogenesis, TCA cycle, pentose phosphate pathway, respiratory complexes, β-oxidation, and synthesis of fatty acids. Gluconeogenesis is uniquely dominant over glycolysis under all surveyed conditions, while the TCA cycle represents an eclectic combination of standard and unusual enzymes. Conclusions The identification of conventional anaerobic enzymes reflects the ability of this protist to survive in low-oxygen environments. Furthermore, its metabolism quickly reacts to restricted carbon availability, suggesting a high metabolic flexibility of diplonemids, which is further reflected in cell morphology and motility, correlating well with their extreme ecological valence.

scholarly journals TCA Cycle Rewiring as Emerging Metabolic Signature of Hepatocellular Carcinoma

Cancers ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 68 ◽  
Author(s):  
Simona Todisco ◽  
Paolo Convertini ◽  
Vito Iacobazzi ◽  
Vittoria Infantino
Keyword(s):  
Gene Expression ◽  
Hepatocellular Carcinoma ◽  
Molecular Mechanisms ◽  
Tca Cycle ◽  
Redox Balance ◽  
Metabolic Reprogramming ◽  
Glutamine Metabolism ◽  
Aberrant Gene Expression ◽  
The Tca Cycle ◽  
Aberrant Gene

Hepatocellular carcinoma (HCC) is a common malignancy. Despite progress in treatment, HCC is still one of the most lethal cancers. Therefore, deepening molecular mechanisms underlying HCC pathogenesis and development is required to uncover new therapeutic strategies. Metabolic reprogramming is emerging as a critical player in promoting tumor survival and proliferation to sustain increased metabolic needs of cancer cells. Among the metabolic pathways, the tricarboxylic acid (TCA) cycle is a primary route for bioenergetic, biosynthetic, and redox balance requirements of cells. In recent years, a large amount of evidence has highlighted the relevance of the TCA cycle rewiring in a variety of cancers. Indeed, aberrant gene expression of several key enzymes and changes in levels of critical metabolites have been observed in many solid human tumors. In this review, we summarize the role of the TCA cycle rewiring in HCC by reporting gene expression and activity dysregulation of enzymes relating not only to the TCA cycle but also to glutamine metabolism, malate/aspartate, and citrate/pyruvate shuttles. Regarding the transcriptional regulation, we focus on the link between NF-κB-HIF1 transcriptional factors and TCA cycle reprogramming. Finally, the potential of metabolic targets for new HCC treatments has been explored.

scholarly journals Glycolysis versus TCA Cycle in the Primate Brain as Measured by Combining 18F-FDG PET and 13C-NMR

2005 ◽  
Vol 25 (11) ◽  
pp. 1418-1423 ◽  
Author(s):  
Fawzi Boumezbeur ◽  
Laurent Besret ◽  
Julien Valette ◽  
Marie-Claude Gregoire ◽  
Thierry Delzescaux ◽  
...  
Keyword(s):  
Tca Cycle ◽  
Glycolytic Flux ◽  
Cerebral Metabolic Rate ◽  
Metabolic Coupling ◽  
Primate Brain ◽  
Positron Emission ◽  
The Tca Cycle ◽  
The Brain ◽  
Good Agreement ◽  
C Nmr

The glycolytic flux (cerebral metabolic rate of glucose CMRglc) and the TCA cycle flux ( VTCA) were measured in the same monkeys by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and 13C NMR spectroscopy, respectively. Registration of nuclear magnetic resonance (NMR) and PET data were used for comparison of CMRglc and VTCA in the exact same area of the brain. Both fluxes were in good agreement with literature values (CMR glc 0.23 ± 0.03 μmol/g min, VTCA = 0.53 ± 0.13 μmol/gmin). The resulting [ CMRglc/VTCA] ratio was 0.46 ± 0.12 ( n = 5, mean ± s.d.), not significantly different from the 0.5 expected when glucose is the sole fuel that is completely oxidized. Our results provide a cross-validation of both techniques. Comparison of CMRglc with VTCA is in agreement with a metabolic coupling between the TCA cycle and glycolysis under normal physiologic conditions.

scholarly journals Absence of retbindin blocks glycolytic flux, disrupts metabolic homeostasis, and leads to photoreceptor degeneration

2021 ◽  
Vol 118 (6) ◽  
pp. e2018956118
Author(s):  
Tirthankar Sinha ◽  
Jianhai Du ◽  
Mustafa S. Makia ◽  
James B. Hurley ◽  
Muna I. Naash ◽  
...  
Keyword(s):  
Retinal Degeneration ◽  
Tca Cycle ◽  
Underlying Mechanism ◽  
Neural Retina ◽  
Pentose Phosphate ◽  
Metabolic Reprogramming ◽  
Glycolytic Flux ◽  
Acid Oxidation ◽  
Atp Production ◽  
Almost All

We previously reported a model of progressive retinal degeneration resulting from the knockout of the retina-specific riboflavin binding protein, retbindin (Rtbdn−/−). We also demonstrated a reduction in neural retinal flavins as a result of the elimination of RTBDN. Given the role of flavins in metabolism, herein we investigated the underlying mechanism of this retinal degeneration by performing metabolomic analyses on predegeneration at postnatal day (P) 45 and at the onset of functional degeneration in the P120 retinas. Metabolomics of hydrophilic metabolites revealed that individual glycolytic products accumulated in the P45 Rtbdn−/− neural retinas along with the elevation of pentose phosphate pathway, while TCA cycle intermediates remained unchanged. This was confirmed by using 13C-labeled flux measurements and immunoblotting, revealing that the key regulatory step of phosphoenolpyruvate to pyruvate was inhibited via down-regulation of the tetrameric pyruvate kinase M2 (PKM2). Separate metabolite assessments revealed that almost all intermediates of acylcarnitine fatty acid oxidation, ceramides, sphingomyelins, and multiple toxic metabolites were significantly elevated in the predegeneration Rtbdn−/− neural retina. Our data show that lack of RTBDN, and hence reduction in flavins, forced the neural retina into repurposing glucose for free-radical mitigation over ATP production. However, such sustained metabolic reprogramming resulted in an eventual metabolic collapse leading to neurodegeneration.

scholarly journals The hexokinase ″HKDC1″ interaction with the mitochondria is essential for hepatocellular carcinoma progression

2021 ◽  
Author(s):  
Md. Wasim Khan ◽  
Alexander Terry ◽  
Medha Priyadarshini ◽  
Grace Guzman ◽  
Jose Cordoba-Chacon ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Mitochondrial Dysfunction ◽  
Tca Cycle ◽  
Metabolic Reprogramming ◽  
Selective Approach ◽  
Glucose Flux ◽  
The Tca Cycle

Hepatocellular carcinoma (HCC) is a leading cause of death from cancer malignancies. Recently, hexokinase domain containing 1 (HKDC1), was shown to have significant overexpression in HCC compared to healthy tissue. Using in vitro and in vivo tools, we examined the role of HKDC1 in HCC progression. Importantly, HKDC1 ablation stops HCC progression by promoting metabolic reprogramming by shifting glucose flux away from the TCA cycle. Next, HKDC1 ablation leads to mitochondrial dysfunction resulting in less cellular energy which cannot be compensated by enhanced glucose uptake. And finally, we show that the interaction of HKDC1 with the mitochondria is essential for its role in HCC progression, and without this mitochondrial interaction mitochondrial dysfunction occurs. In sum, HKDC1 is highly expressed in HCC cells compared to normal hepatocytes, therefore targeting HKDC1, specifically its interaction with the mitochondria, reveals a highly selective approach to target cancer cells in HCC.

scholarly journals The breast cancer oncogene IKKε coordinates mitochondrial function and serine metabolism

2019 ◽  
Author(s):  
Ruoyan Xu ◽  
William Jones ◽  
Ewa Wilcz-Villega ◽  
A. Sofia H. Costa ◽  
Vinothini Rajeeve ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Breast Cancer Cells ◽  
Tca Cycle ◽  
Metabolic Reprogramming ◽  
Metabolic Phenotype ◽  
Human Breast ◽  
Iκb Kinase ◽  
The Tca Cycle ◽  
Serine Biosynthesis ◽  
Serine Metabolism

ABSTRACTThe IκB kinase ε (IKKε) is a key molecule at the crossroads of inflammation and cancer. Known for its role as an activator of NFκB and IRF3 signalling leading to cytokine secretion, the kinase is also a breast cancer oncogene, overexpressed in a variety of tumours. However, to what extent IKKε remodels cellular metabolism is currently unknown. Here we used a combination of metabolomics and phosphoproteomics to show that IKKε orchestrates a complex metabolic reprogramming that affects mitochondrial metabolism and serine biosynthesis. Acting independently of its canonical signalling role, IKKε upregulates the serine biosynthesis pathway (SBP) mainly by limiting glucose and pyruvate derived anaplerosis of the TCA cycle. In turn, this elicits activation of the transcription factor ATF4 and upregulation of the SBP genes. Importantly, pharmacological inhibition of the IKKε-induced metabolic phenotype reduces proliferation of breast cancer cells. Finally, we show that in a set of basal ER negative and highly proliferative human breast cancer tumours, IKKε and PSAT1 expression levels are positively correlated corroborating the link between IKKε and the SBP in the clinical context.

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