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Nature May 2024Glucocorticoids represent the mainstay of therapy for a broad spectrum of immune-mediated inflammatory diseases. However, the molecular mechanisms underlying their...
Glucocorticoids represent the mainstay of therapy for a broad spectrum of immune-mediated inflammatory diseases. However, the molecular mechanisms underlying their anti-inflammatory mode of action have remained incompletely understood. Here we show that the anti-inflammatory properties of glucocorticoids involve reprogramming of the mitochondrial metabolism of macrophages, resulting in increased and sustained production of the anti-inflammatory metabolite itaconate and consequent inhibition of the inflammatory response. The glucocorticoid receptor interacts with parts of the pyruvate dehydrogenase complex whereby glucocorticoids provoke an increase in activity and enable an accelerated and paradoxical flux of the tricarboxylic acid (TCA) cycle in otherwise pro-inflammatory macrophages. This glucocorticoid-mediated rewiring of mitochondrial metabolism potentiates TCA-cycle-dependent production of itaconate throughout the inflammatory response, thereby interfering with the production of pro-inflammatory cytokines. By contrast, artificial blocking of the TCA cycle or genetic deficiency in aconitate decarboxylase 1, the rate-limiting enzyme of itaconate synthesis, interferes with the anti-inflammatory effects of glucocorticoids and, accordingly, abrogates their beneficial effects during a diverse range of preclinical models of immune-mediated inflammatory diseases. Our findings provide important insights into the anti-inflammatory properties of glucocorticoids and have substantial implications for the design of new classes of anti-inflammatory drugs.
Topics: Animals; Female; Humans; Male; Mice; Anti-Inflammatory Agents; Carboxy-Lyases; Citric Acid Cycle; Cytokines; Glucocorticoids; Hydro-Lyases; Inflammation; Macrophages; Mice, Inbred C57BL; Mitochondria; Pyruvate Dehydrogenase Complex; Receptors, Glucocorticoid; Succinates; Enzyme Activation
PubMed: 38600378
DOI: 10.1038/s41586-024-07282-7 -
Cell Metabolism May 2022The folic acid cycle mediates the transfer of one-carbon (1C) units to support nucleotide biosynthesis. While the importance of serine as a mitochondrial and cytosolic...
The folic acid cycle mediates the transfer of one-carbon (1C) units to support nucleotide biosynthesis. While the importance of serine as a mitochondrial and cytosolic donor of folate-mediated 1C units in cancer cells has been thoroughly investigated, a potential role of glycine oxidation remains unclear. We developed an approach for quantifying mitochondrial glycine cleavage system (GCS) flux by combining stable and radioactive isotope tracing with computational flux decomposition. We find high GCS flux in hepatocellular carcinoma (HCC), supporting nucleotide biosynthesis. Surprisingly, other than supplying 1C units, we found that GCS is important for maintaining protein lipoylation and mitochondrial activity. Genetic silencing of glycine decarboxylase inhibits the lipoylation and activity of pyruvate dehydrogenase and impairs tumor growth, suggesting a novel drug target for HCC. Considering the physiological role of liver glycine cleavage, our results support the notion that tissue of origin plays an important role in tumor-specific metabolic rewiring.
Topics: Carcinoma, Hepatocellular; Folic Acid; Glycine; Glycine Dehydrogenase (Decarboxylating); Humans; Lipoylation; Liver Neoplasms; Mitochondrial Proteins; Nucleotides
PubMed: 35508111
DOI: 10.1016/j.cmet.2022.04.006 -
Journal of Cellular and Molecular... Jun 2020Reducing infarct size during a cardiac ischaemic-reperfusion episode is still of paramount importance, because the extension of myocardial necrosis is an important risk... (Review)
Review
Reducing infarct size during a cardiac ischaemic-reperfusion episode is still of paramount importance, because the extension of myocardial necrosis is an important risk factor for developing heart failure. Cardiac ischaemia-reperfusion injury (IRI) is in principle a metabolic pathology as it is caused by abruptly halted metabolism during the ischaemic episode and exacerbated by sudden restart of specific metabolic pathways at reperfusion. It should therefore not come as a surprise that therapy directed at metabolic pathways can modulate IRI. Here, we summarize the current knowledge of important metabolic pathways as therapeutic targets to combat cardiac IRI. Activating metabolic pathways such as glycolysis (eg AMPK activators), glucose oxidation (activating pyruvate dehydrogenase complex), ketone oxidation (increasing ketone plasma levels), hexosamine biosynthesis pathway (O-GlcNAcylation; administration of glucosamine/glutamine) and deacetylation (activating sirtuins 1 or 3; administration of NAD -boosting compounds) all seem to hold promise to reduce acute IRI. In contrast, some metabolic pathways may offer protection through diminished activity. These pathways comprise the malate-aspartate shuttle (in need of novel specific reversible inhibitors), mitochondrial oxygen consumption, fatty acid oxidation (CD36 inhibitors, malonyl-CoA decarboxylase inhibitors) and mitochondrial succinate metabolism (malonate). Additionally, protecting the cristae structure of the mitochondria during IR, by maintaining the association of hexokinase II or creatine kinase with mitochondria, or inhibiting destabilization of F F -ATPase dimers, prevents mitochondrial damage and thereby reduces cardiac IRI. Currently, the most promising and druggable metabolic therapy against cardiac IRI seems to be the singular or combined targeting of glycolysis, O-GlcNAcylation and metabolism of ketones, fatty acids and succinate.
Topics: Animals; Energy Metabolism; Humans; Mitochondria, Heart; Molecular Targeted Therapy; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium
PubMed: 32384583
DOI: 10.1111/jcmm.15180 -
Biotechnology Journal Jul 2019Lactobacilli are members of a large family involved in industrial food fermentation, therapeutics, and health promotion. However, the development of genetic manipulation...
Lactobacilli are members of a large family involved in industrial food fermentation, therapeutics, and health promotion. However, the development of genetic manipulation tools for this genus lags behind its relative industrial and medical significance. The development of clustered regularly interspaced short palindromic repeat (CRISPR)-based genome engineering for Lactobacillus is now underway. However, some Lactobacillus species are sensitive to CRISPR-Cas9 induced double strand breaks (DSBs) due to a deficiency in homology-directed repair (HDR), which allows chromosomal genetic editing. Here, phage-derived RecE/T is coupled with CRISPR-Cas9 and the transcriptional activity of broad-spectrum host promoters is assessed to set up a versatile toolbox containing a recombination helper plasmid and a broad host CRISPR-Cas9 editing plasmid, which enables efficient genome editing in Lactobacillus plantarum (L. plantarum) WCFS1 and Lactobacillus brevis (L. brevis) ATCC367. The RecE/T-assisted CRISPR-Cas9 toolbox realizes single gene deletions at an efficiency of 50-100% in seven days. Furthermore, the chromosomal gene replacement of Lp_0537 using a P -pyruvate decarboxylase (pdc) expression cassette is accomplished with an efficiency of 35.7%. This study establises a RecE/T-assisted CRISPR genome editing toolbox for L. plantarum WCFS1 and L. brevis ATCC367 and also demonstrate that RecE/T-assisted CRISPR-Cas9 is an effective genome editing system, which can be readily implemented in Lactobacilli.
Topics: CRISPR-Cas Systems; Gene Editing; Genome, Bacterial; Lactobacillus; Promoter Regions, Genetic
PubMed: 30927506
DOI: 10.1002/biot.201800690 -
Cell Oct 2018Acetate is a major nutrient that supports acetyl-coenzyme A (Ac-CoA) metabolism and thus lipogenesis and protein acetylation. However, its source is unclear. Here, we...
Acetate is a major nutrient that supports acetyl-coenzyme A (Ac-CoA) metabolism and thus lipogenesis and protein acetylation. However, its source is unclear. Here, we report that pyruvate, the end product of glycolysis and key node in central carbon metabolism, quantitatively generates acetate in mammals. This phenomenon becomes more pronounced in the context of nutritional excess, such as during hyperactive glucose metabolism. Conversion of pyruvate to acetate occurs through two mechanisms: (1) coupling to reactive oxygen species (ROS) and (2) neomorphic enzyme activity from keto acid dehydrogenases that enable function as pyruvate decarboxylases. Further, we demonstrate that de novo acetate production sustains Ac-CoA pools and cell proliferation in limited metabolic environments, such as during mitochondrial dysfunction or ATP citrate lyase (ACLY) deficiency. By virtue of de novo acetate production being coupled to mitochondrial metabolism, there are numerous possible regulatory mechanisms and links to pathophysiology.
Topics: ATP Citrate (pro-S)-Lyase; Acetates; Acetyl Coenzyme A; Acetylation; Animals; Female; Glucose; Glycolysis; Lipogenesis; Male; Mammals; Mice; Mice, Inbred C57BL; Mitochondria; Oxidoreductases; Pyruvate Decarboxylase; Pyruvic Acid; Reactive Oxygen Species
PubMed: 30245009
DOI: 10.1016/j.cell.2018.08.040 -
The Protein Journal Aug 2021The accumulation of carbon dioxide in the atmosphere as a result of human activities has caused a number of adverse circumstances in the world. For this reason, the... (Review)
Review
The accumulation of carbon dioxide in the atmosphere as a result of human activities has caused a number of adverse circumstances in the world. For this reason, the proposed solutions lie within the aim of reducing carbon dioxide emissions have been quite valuable. However, as the human activity continues to increase on this planet, the possibility of reducing carbon dioxide emissions decreases with the use of conventional methods. The emergence of compounds than can be used in different fields by converting the released carbon dioxide into different chemicals will construct a fundamental solution to the problem. Although electro-catalysis or photolithography methods have emerged for this purpose, they have not been able to achieve successful results. Alternatively, another proposed solution are enzyme based systems. Among the enzyme-based systems, pyruvate decarboxylase, carbonic anhydrase and dehydrogenases have been the most studied enzymes. Pyruvate dehydrogenase and carbonic anhydrase have either been an expensive method or were incapable of producing the desired result due to the reaction cascade they catalyze. However, the studies reporting the production of industrial chemicals from carbon dioxide using dehydrogenases and in particular, the formate dehydrogenase enzyme, have been remarkable. Moreover, reported studies have shown the existence of more active and stable enzymes, especially the dehydrogenase family that can be identified from the biome. In addition to this, their redesign through protein engineering can have an immense contribution to the increased use of enzyme-based methods in CO reduction, resulting in an enormous expansion of the industrial capacity.
Topics: Carbon Dioxide; Catalysis; Formate Dehydrogenases; Ketone Oxidoreductases
PubMed: 34100161
DOI: 10.1007/s10930-021-10007-8 -
Current Opinion in Biotechnology Jun 2015We compare a number of different strategies that have been pursued to engineer thermophilic microorganisms for increased ethanol production. Ethanol production from... (Review)
Review
We compare a number of different strategies that have been pursued to engineer thermophilic microorganisms for increased ethanol production. Ethanol production from pyruvate can proceed via one of four pathways, which are named by the key pyruvate dissimilating enzyme: pyruvate decarboxylase (PDC), pyruvate dehydrogenase (PDH), pyruvate formate lyase (PFL), and pyruvate ferredoxin oxidoreductase (PFOR). For each of these pathways except PFL, we see examples where ethanol production has been engineered with a yield of >90% of the theoretical maximum. In each of these cases, this engineering was achieved mainly by modulating expression of native genes. We have not found an example where a thermophilic ethanol production pathway has been transferred to a non-ethanol-producing organism to produce ethanol at high yield. A key reason for the lack of transferability of ethanol production pathways is the current lack of understanding of the enzymes involved.
Topics: Adenosine Triphosphate; Amino Acids; Ethanol; Hot Temperature; Pyruvic Acid
PubMed: 25745810
DOI: 10.1016/j.copbio.2015.02.006 -
BMC Research Notes May 2021Zymomonas mobilis is an alpha-proteobacterium with a rapid ethanologenic pathway, involving Entner-Doudoroff (E-D) glycolysis, pyruvate decarboxylase (Pdc) and two...
OBJECTIVE
Zymomonas mobilis is an alpha-proteobacterium with a rapid ethanologenic pathway, involving Entner-Doudoroff (E-D) glycolysis, pyruvate decarboxylase (Pdc) and two alcohol dehydrogenase (ADH) isoenzymes. Pyruvate is the end-product of the E-D pathway and the substrate for Pdc. Construction and study of Pdc-deficient strains is of key importance for Z. mobilis metabolic engineering, because the pyruvate node represents the central branching point, most novel pathways divert from ethanol synthesis. In the present work, we examined the aerobic metabolism of a strain with partly inactivated Pdc.
RESULTS
Relative to its parent strain the mutant produced more pyruvate. Yet, it also yielded more acetaldehyde, the product of the Pdc reaction and the substrate for ADH, although the bulk ADH activity was similar in both strains, while the Pdc activity in the mutant was reduced by half. Simulations with the kinetic model of Z. mobilis E-D pathway indicated that, for the observed acetaldehyde to ethanol production ratio in the mutant, the ratio between its respiratory NADH oxidase and ADH activities should be significantly higher, than the measured values. Implications of this finding for the directionality of the ADH isoenzyme operation in vivo and interactions between ADH and Pdc are discussed.
Topics: Alcohol Dehydrogenase; Metabolic Engineering; Pyruvate Decarboxylase; Respiration; Zymomonas
PubMed: 34049566
DOI: 10.1186/s13104-021-05625-5 -
Biochimica Et Biophysica Acta Sep 2014Studies of thiamine diphosphate-dependent enzymes appear to have commenced in 1937, with the isolation of the coenzyme of yeast pyruvate decarboxylase, which was... (Review)
Review
Studies of thiamine diphosphate-dependent enzymes appear to have commenced in 1937, with the isolation of the coenzyme of yeast pyruvate decarboxylase, which was demonstrated to be a diphosphoric ester of thiamine. For quite a long time, these studies were largely focused on enzymes decarboxylating α-keto acids, such as pyruvate decarboxylase and pyruvate dehydrogenase complexes. Transketolase, discovered independently by Racker and Horecker in 1953 (and named by Racker) [1], did not receive much attention until 1992, when crystal X-ray structure analysis of the enzyme from Saccharomyces cerevisiae was performed [2]. These data, together with the results of site-directed mutagenesis, made it possible to understand in detail the mechanism of thiamine diphosphate-dependent catalysis. Some progress was also made in studies of the functional properties of transketolase. The last review on transketolase, which was fairly complete, appeared in 1998 [3]. Therefore, the publication of this paper should not seem premature.
Topics: Binding Sites; Calcium; Coenzymes; Glycolysis; Kinetics; Models, Molecular; Pentose Phosphate Pathway; Protein Multimerization; Protein Structure, Tertiary; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Substrate Specificity; Thiamine Pyrophosphate; Transketolase
PubMed: 24929114
DOI: 10.1016/j.bbapap.2014.06.003 -
Journal of Forensic and Legal Medicine Apr 2022Although previous cases of ethyl alcohol production by microorganisms present in the intestines, referred to as auto-brewery syndrome (ABS), have been reported, a recent...
Although previous cases of ethyl alcohol production by microorganisms present in the intestines, referred to as auto-brewery syndrome (ABS), have been reported, a recent case in our practice was characterized by the production of alcohol in the oral cavity. Our research indicates that legally significant levels of ethyl alcohol can be detected in exhaled air in cases where there has been no alcohol consumption but where the subject has oral candidiasis. In such cases, following the consumption of foods containing carbohydrates, a fermentation process occurs in the mouth, the first stage of which is glycolysis, proceeding according to the Embden-Meyerhof-Parnas pathway, which is typical in eukaryotes. The main organic substrate in this case is glucose, which is formed in the oral cavity from disaccharides (maltose, sucrose) by the activity of α-amylase. Some mutated fungal strains of the genus Candida acquire the ability to break down sucrose and produce glucoamylase. Glucose is converted into glyceraldehyde 3-phosphate and then into pyruvate. The next stage of fermentation is the decarboxylation of pyruvate into acetaldehyde, a reaction catalyzed by pyruvate decarboxylase. The final stage is the reduction of acetaldehyde to ethanol by alcohol dehydrogenase. Such endogenous production of alcohol can be confused with its consumption, which can cause not only legal, but also social and medical problems.
Topics: Ethanol; Fermentation; Glucose; Humans
PubMed: 35290834
DOI: 10.1016/j.jflm.2022.102333