bims-mepmim Biomed News
on Metabolites in pathological microenvironments and immunometabolism
Issue of 2022–03–27
53 papers selected by
Erika Mariana Palmieri, NIH/NCI Laboratory of Cancer ImmunoMetabolism
  1. Metabolic Reprogramming of Ovarian Cancer Spheroids during Adhesion.
  2. Hallmarks of Metabolic Reprogramming and Their Role in Viral Pathogenesis.
  3. Roles of microRNAs in metabolic reprogramming of breast cancer.
  4. Activation of Drp1 promotes fatty acids-induced metabolic reprograming to potentiate Wnt signaling in colon cancer.
  5. Integrated metabolomic and transcriptomic analysis identifies benzo[a]pyrene-induced characteristic metabolic reprogramming during accumulation of lipids and reactive oxygen species in macrophages.
  6. Potential Metabolite Markers for Pancreatic Cancer Identified by Metabolomic Analysis of Induced Cancer-Associated Fibroblasts.
  7. Lipid Metabolism Interplay in CRC-An Update.
  8. A non-dividing cell population with high pyruvate dehydrogenase kinase activity regulates metabolic heterogeneity and tumorigenesis in the intestine.
  9. A suppressor of dioxygenase inhibition in a yeast model of SDH deficiency.
  10. Divergent Metabolic Effects of Metformin Merge to Enhance Eicosapentaenoic Acid Metabolism and Inhibit Ovarian Cancer In Vivo.
  11. [Cholesterol Metabolism and Tumor Immunity].
  12. The regulation of cardiac intermediary metabolism by NADPH oxidases.
  13. Chronic Lactate Exposure Decreases Mitochondrial Function by Inhibition of Fatty Acid Uptake and Cardiolipin Alterations in Neonatal Rat Cardiomyocytes.
  14. The Interplay between Cell-Extracellular Matrix Interaction and Mitochondria Dynamics in Cancer.
  15. The glucose transporter GLUT3 controls T helper 17 cell responses through glycolytic-epigenetic reprogramming.
  16. Towards Mapping Mouse Metabolic Tissue Atlas by Mid-Infrared Imaging with Heavy Water Labeling.
  17. Thymidine Kinase 1 Drives Skin Cutaneous Melanoma Malignant Progression and Metabolic Reprogramming.
  18. Untargeted Metabolomics Showed Accumulation of One-Carbon Metabolites to Facilitate DNA Methylation during Extracellular Matrix Detachment of Cancer Cells.
  19. Venetoclax-Resistant MV4-11 Leukemic Cells Activate PI3K/AKT Pathway for Metabolic Reprogramming and Redox Adaptation for Survival.
  20. Maternal Nutrient Restriction Disrupts Gene Expression and Metabolites Associated with Urea Cycle, Steroid Synthesis, Glucose Homeostasis, and Glucuronidation in Fetal Calf Liver.
  21. Polyunsaturated Fatty Acid-Enriched Lipid Fingerprint of Glioblastoma Proliferative Regions Is Differentially Regulated According to Glioblastoma Molecular Subtype.
  22. 1,25-dihydroxyvitamin D3 suppresses CD4+ T cell effector functionality by inhibition of glycolysis.
  23. Editorial: Metabolism and Cell Adhesion in Cancer.
  24. The Matrisome Is Associated with Metabolic Reprograming in Stem-like Phenotypes of Gastric Cancer.
  25. CD8+ T cells PUF(A)ing the flames of cancer ferroptotic cell death.
  26. Differential Metabotypes in Synovial Fibroblasts and Synovial Fluid in Hip Osteoarthritis Patients Support Inflammatory Responses.
  27. Metabolic Response in Endothelial Cells to Catecholamine Stimulation Associated with Increased Vascular Permeability.
  28. Editorial: The Role of Systemic and Cellular Metabolism on Susceptibility to Infections and Responsiveness to Vaccination.
  29. Mitochondrial Respiration in Response to Iron Deficiency Anemia: Comparison of Peripheral Blood Mononuclear Cells and Liver.
  30. [Urine metabolomics study of hepatocellular carcinoma].
  31. Nuclear-Mitochondrial Interactions.
  32. NAD+ centric mechanisms and molecular determinants of skeletal muscle disease and aging.
  33. Distinct Effects of High-Fat and High-Phosphate Diet on Glucose Metabolism and the Response to Voluntary Exercise in Male Mice.
  34. Lactate Enhances Mouse ES Cell Differentiation Toward XEN Cells In Vitro.
  35. Evaluation of Metabolic Changes in Acute Intermittent Porphyria Patients by Targeted Metabolomics.
  36. Bcl-xL enforces a slow-cycling state necessary for survival in the nutrient-deprived microenvironment of pancreatic cancer.
  37. Reprogramming of arachidonate metabolism confers temozolomide resistance to glioblastoma through enhancing mitochondrial activity in fatty acid oxidation.
  38. Comprehensive molecular characterization and identification of prognostic signature in stomach adenocarcinoma on the basis of energy-metabolism-related genes.
  39. A Metabolic Network Mediating the Cycling of Succinate, a Product of ROS Detoxification into α-Ketoglutarate, an Antioxidant.
  40. Hexokinase 1 cellular localization regulates the metabolic fate of glucose.
  41. Evidence That Substantia Nigra Pars Compacta Dopaminergic Neurons Are Selectively Vulnerable to Oxidative Stress Because They Are Highly Metabolically Active.
  42. Combined HP 13C Pyruvate and 13C-Glucose Fluxomic as a Potential Marker of Response to Targeted Therapies in YUMM1.7 Melanoma Xenografts.
  43. Combination of Electrochemistry and Mass Spectrometry to Study Nitric Oxide Metabolism and Its Modulation by Compound K in Breast Cancer Cells.
  44. Lactate metabolism in rheumatoid arthritis: Pathogenic mechanisms and therapeutic intervention with natural compounds.
  45. Oxidative Stress Differentially Influences the Survival and Metabolism of Cells in the Melanoma Microenvironment.
  46. Ketogenic HMG-CoA lyase and its product β-hydroxybutyrate promote pancreatic cancer progression.
  47. Tumor Cell Glycolysis-At the Crossroad of Epithelial-Mesenchymal Transition and Autophagy.
  48. Thyroid hormone regulates glutamine metabolism and anaplerotic fluxes by inducing mitochondrial glutamate aminotransferase GPT2.
  49. PHGDH is required for germinal center formation and is a therapeutic target in MYC-driven lymphoma.
  50. NRF2 and Key Transcriptional Targets in Melanoma Redox Manipulation.
  51. Analysis of N6-methyladenosine-related lncRNAs in the tumor immune microenvironment and their prognostic role in pancreatic cancer.
  52. PPARdelta activation induces metabolic and contractile maturation of human pluripotent stem-cell-derived cardiomyocytes.
  53. Sulfide Oxidation Evidences the Immediate Cellular Response to a Decrease in the Mitochondrial ATP/O2 Ratio.
  1. Cancers (Basel). 2022 Mar 09. pii: 1399. [Epub ahead of print]14(6):
    Metabolic Reprogramming of Ovarian Cancer Spheroids during Adhesion.
    Stephanie L E Compton, Joseph P Grieco, Benita Gollamudi, Eric Bae, Jennifer H Van Mullekom, Eva M Schmelz.
      Ovarian cancer remains a deadly disease and its recurrence disease is due in part to the presence of disseminating ovarian cancer aggregates not removed by debulking surgery. During dissemination in a dynamic ascitic environment, the spheroid cells' metabolism is characterized by low respiration and fragmented mitochondria, a metabolic phenotype that may not support secondary outgrowth after adhesion. Here, we investigated how adhesion affects cellular respiration and substrate utilization of spheroids mimicking early stages of secondary metastasis. Using different glucose and oxygen levels, we investigated cellular metabolism at early time points of adherence (24 h and less) comparing slow and fast-developing disease models. We found that adhesion over time showed changes in cellular energy metabolism and substrate utilization, with a switch in the utilization of mostly glutamine to glucose but no changes in fatty acid oxidation. Interestingly, low glucose levels had less of an impact on cellular metabolism than hypoxia. A resilience to culture conditions and the capacity to utilize a broader spectrum of substrates more efficiently distinguished the highly aggressive cells from the cells representing slow-developing disease, suggesting a flexible metabolism contributes to the stem-like properties. These results indicate that adhesion to secondary sites initiates a metabolic switch in the oxidation of substrates that could support outgrowth and successful metastasis.
    Keywords:  glucose uptake; glutamine; hypoxia; metabolism; mitochondrial function; ovarian cancer; respiration; spheroid; sphingosine-1-phosphate; substrate utilization
    DOI:  https://doi.org/10.3390/cancers14061399
  2. Viruses. 2022 Mar 14. pii: 602. [Epub ahead of print]14(3):
    Hallmarks of Metabolic Reprogramming and Their Role in Viral Pathogenesis.
    Charles N S Allen, Sterling P Arjona, Maryline Santerre, Bassel E Sawaya.
      Metabolic reprogramming is a hallmark of cancer and has proven to be critical in viral infections. Metabolic reprogramming provides the cell with energy and biomass for large-scale biosynthesis. Based on studies of the cellular changes that contribute to metabolic reprogramming, seven main hallmarks can be identified: (1) increased glycolysis and lactic acid, (2) increased glutaminolysis, (3) increased pentose phosphate pathway, (4) mitochondrial changes, (5) increased lipid metabolism, (6) changes in amino acid metabolism, and (7) changes in other biosynthetic and bioenergetic pathways. Viruses depend on metabolic reprogramming to increase biomass to fuel viral genome replication and production of new virions. Viruses take advantage of the non-metabolic effects of metabolic reprogramming, creating an anti-apoptotic environment and evading the immune system. Other non-metabolic effects can negatively affect cellular function. Understanding the role metabolic reprogramming plays in viral pathogenesis may provide better therapeutic targets for antivirals.
    Keywords:  Warburg effect; amino acid metabolism; biomass; biosynthetic and bioenergetic pathways; glutaminolysis; glycolysis; lipid metabolism; metabolic reprogramming; mitochondria; pentose phosphate pathway; viral replication; virus
    DOI:  https://doi.org/10.3390/v14030602
  3. J Pak Med Assoc. 2022 Feb;72(2): 312-316
    Roles of microRNAs in metabolic reprogramming of breast cancer.
    Fan Feng, Qinqin Yu, Feng Zhang.
      Breast cancer cells exhibit deregulated metabolism. They require increased glucose uptake and glycolysis-associated enzymes to produce adenosine triphosphate by aerobic glycolysis rather than oxidative phosphorylation. Glutamine metabolism and fatty acid synthesis are also enhanced to meet the rapid and sustained cell growth. Triple-negative breast cancer and human epidermal growth factor receptor-2-positive breast cancers demonstrate significant metabolic reprogramming with increased levels of glucose and glutamine metabolism. Increasing evidences also suggest that micro-ribonucleic acids play important roles in the regulation of metabolic enzymes of breast cancer cells in post-transcriptional manner. Human epidermal growth factor receptor-2 and oestrogen receptor signalling pathways could have crosstalk with micro-ribonucleic acids in metabolic regulation network. The current narrative review was planned to go through recent advances on the role of micro-ribonucleic acids on metabolic reprogramming in breast cancer cells.
    Keywords:   Breast cancer, Phenotype, miRNA, Metabolic reprogramming, Glycolysis, Glutamine.
    DOI:  https://doi.org/10.47391/JPMA.1132
  4. Cell Death Differ. 2022 Mar 24.
    Activation of Drp1 promotes fatty acids-induced metabolic reprograming to potentiate Wnt signaling in colon cancer.
    Xiaopeng Xiong, Sumati Hasani, Lyndsay E A Young, Dylan R Rivas, Ashley T Skaggs, Rebecca Martinez, Chi Wang, Heidi L Weiss, Matthew S Gentry, Ramon C Sun, Tianyan Gao.
      Cancer cells are known for their ability to adapt variable metabolic programs depending on the availability of specific nutrients. Our previous studies have shown that uptake of fatty acids alters cellular metabolic pathways in colon cancer cells to favor fatty acid oxidation. Here, we show that fatty acids activate Drp1 to promote metabolic plasticity in cancer cells. Uptake of fatty acids (FAs) induces mitochondrial fragmentation by promoting ERK-dependent phosphorylation of Drp1 at the S616 site. This increased phosphorylation of Drp1 enhances its dimerization and interaction with Mitochondrial Fission Factor (MFF) at the mitochondria. Consequently, knockdown of Drp1 or MFF attenuates fatty acid-induced mitochondrial fission. In addition, uptake of fatty acids triggers mitophagy via a Drp1- and p62-dependent mechanism to protect mitochondrial integrity. Moreover, results from metabolic profiling analysis reveal that silencing Drp1 disrupts cellular metabolism and blocks fatty acid-induced metabolic reprograming by inhibiting fatty acid utilization. Functionally, knockdown of Drp1 decreases Wnt/β-catenin signaling by preventing fatty acid oxidation-dependent acetylation of β-catenin. As a result, Drp1 depletion inhibits the formation of tumor organoids in vitro and xenograft tumor growth in vivo. Taken together, our study identifies Drp1 as a key mediator that connects mitochondrial dynamics with fatty acid metabolism and cancer cell signaling.
    DOI:  https://doi.org/10.1038/s41418-022-00974-5
  5. Sci Total Environ. 2022 Mar 18. pii: S0048-9697(22)01778-8. [Epub ahead of print] 154685
    Integrated metabolomic and transcriptomic analysis identifies benzo[a]pyrene-induced characteristic metabolic reprogramming during accumulation of lipids and reactive oxygen species in macrophages.
    Guozhu Ye, Wenjia Lu, Luyun Zhang, Han Gao, Xu Liao, Xu Zhang, Han Zhang, Jinsheng Chen, Qiansheng Huang.
      Polycyclic aromatic hydrocarbon exposure is a major risk factor for cardiovascular diseases. Macrophage lipid accumulation is a characteristic molecular event in the pathophysiology of cardiovascular diseases. Metabolic reprogramming is an intervention target for diseases and toxic effects of environmental pollutants. However, comprehensive metabolic reprogramming related to BaP-induced macrophage lipid accumulation is currently unexplored. Therefore, metabolomics and transcriptomics were conducted to unveil relevant metabolic reprogramming in BaP-exposed macrophages, and to discover potential intervention targets. Metabolomics revealed that most amino acids, nucleotides, monosaccharides, and organic acids were significantly decreased, while most fatty acids and steroids accumulated in BaP-exposed macrophages. Transcriptomics showed that fatty acid synthesis and oxidation, and steroid synthesis and export were decreased, while import of fatty acids and steroids was increased, indicating potential roles of lipid transport in macrophage lipid accumulation following BaP exposure. Meanwhile, alanine, aspartate and glutamate metabolism, branched-chain amino acid degradation, nucleotide synthesis, monosaccharide import, pentose phosphate pathway, citrate synthesis, and glycolysis were decreased, while nucleotide degradation was increased, thus inducing decreases in most amino acids, nucleotides, monosaccharides, and organic acids in BaP-exposed macrophages. Additionally, increases in oxidative stress and the activation of antioxidant systems were observed in BaP-exposed macrophages, which was evinced by increases in reactive oxygen species, and the activation of Fenton reaction, Vdac2/3, Sod2, and Nrf2. Moreover, BaP-induced accumulation of reactive oxygen species and lipids in macrophages could be abolished by epigallocatechin-3-gallate. Quantitative PCR showed that BaP exposure activated aryl hydrocarbon receptor signaling and promoted the proinflammatory phenotype in macrophages, and these effects were inhibited or even abolished by the separate treatment with epigallocatechin-3-gallate or CH-223191, suggesting the regulatory role of aryl hydrocarbon receptor signaling in BaP-induced toxic effects. This study provides novel insights into the toxic effects of polycyclic aromatic hydrocarbons on macrophage metabolism and potential intervention targets.
    Keywords:  Amino acid metabolism; Aryl hydrocarbon receptor; Lipid metabolism; Nucleotide metabolism; Redox homeostasis
    DOI:  https://doi.org/10.1016/j.scitotenv.2022.154685
  6. Cancers (Basel). 2022 Mar 08. pii: 1375. [Epub ahead of print]14(6):
    Potential Metabolite Markers for Pancreatic Cancer Identified by Metabolomic Analysis of Induced Cancer-Associated Fibroblasts.
    Yoshihiro Miyazaki, Nobuhito Mori, Yuka Akagi, Tatsuya Oda, Yasuyuki S Kida.
      Cancer-associated fibroblasts (CAFs) in the tumor microenvironment perform glycolysis to produce energy, i.e., ATP. Since the origin of CAFs is unidentified, it is not determined whether the intracellular metabolism transitions from oxidative phosphorylation (OXPHOS) to glycolysis when normal tissue fibroblasts differentiate into CAFs. In this study, we established an experimental system and induced the in vitro differentiation of mesenchymal stem cells (MSCs) to CAFs. Additionally, we performed metabolomic and RNA-sequencing analyses before and after differentiation to investigate changes in the intracellular metabolism. Consequently, we discovered that OXPHOS, which was the primary intracellular metabolism in MSCs, was reprogrammed to glycolysis. Furthermore, we analyzed the metabolites in pancreatic tumor tissues in a mice model. The metabolites extracted as candidates in the in vitro experiments were also detected in the in vivo experiments. Thus, we conclude that normal tissue fibroblasts that differentiate into CAFs undergo a metabolic reprogramming from OXPHOS to glycolysis. Moreover, we identified the CAF-specific metabolites expressed during metabolic reprogramming as potential future biomarkers for pancreatic cancer.
    Keywords:  cancer-associated fibroblasts; cell differentiation; glycolysis; intracellular metabolism; oxidative phosphorylation; pancreatic cancer; tumor microenvironment
    DOI:  https://doi.org/10.3390/cancers14061375
  7. Metabolites. 2022 Feb 26. pii: 213. [Epub ahead of print]12(3):
    Lipid Metabolism Interplay in CRC-An Update.
    Dana Krauß, Ourania Fari, Maria Sibilia.
      Colorectal cancer (CRC) to date still ranks as one of the deadliest cancer entities globally, and despite recent advances, the incidence in young adolescents is dramatically increasing. Lipid metabolism has recently received increased attention as a crucial element for multiple aspects of carcinogenesis and our knowledge of the underlying mechanisms is steadily growing. However, the mechanism how fatty acid metabolism contributes to CRC is still not understood in detail. In this review, we aim to summarize our vastly growing comprehension and the accompanied complexity of cellular fatty acid metabolism in CRC by describing inputs and outputs of intracellular free fatty acid pools and how these contribute to cancer initiation, disease progression and metastasis. We highlight how different lipid pathways can contribute to the aggressiveness of tumors and affect the prognosis of patients. Furthermore, we focus on the role of lipid metabolism in cell communication and interplay within the tumor microenvironment (TME) and beyond. Understanding these interactions in depth might lead to the discovery of novel markers and new therapeutic interventions for CRC. Finally, we discuss the crucial role of fatty acid metabolism as new targetable gatekeeper in colorectal cancer.
    Keywords:  colorectal cancer; immunometabolism; lipid metabolism; metabolites
    DOI:  https://doi.org/10.3390/metabo12030213
  8. Nat Commun. 2022 Mar 21. 13(1): 1503
    A non-dividing cell population with high pyruvate dehydrogenase kinase activity regulates metabolic heterogeneity and tumorigenesis in the intestine.
    Carlos Sebastian, Christina Ferrer, Maria Serra, Jee-Eun Choi, Nadia Ducano, Alessia Mira, Manasvi S Shah, Sylwia A Stopka, Andrew J Perciaccante, Claudio Isella, Daniel Moya-Rull, Marianela Vara-Messler, Silvia Giordano, Elena Maldi, Niyati Desai, Diane E Capen, Enzo Medico, Murat Cetinbas, Ruslan I Sadreyev, Dennis Brown, Miguel N Rivera, Anna Sapino, David T Breault, Nathalie Y R Agar, Raul Mostoslavsky.
      Although reprogramming of cellular metabolism is a hallmark of cancer, little is known about how metabolic reprogramming contributes to early stages of transformation. Here, we show that the histone deacetylase SIRT6 regulates tumor initiation during intestinal cancer by controlling glucose metabolism. Loss of SIRT6 results in an increase in the number of intestinal stem cells (ISCs), which translates into enhanced tumor initiating potential in APCmin mice. By tracking down the connection between glucose metabolism and tumor initiation, we find a metabolic compartmentalization within the intestinal epithelium and adenomas, where a rare population of cells exhibit features of Warburg-like metabolism characterized by high pyruvate dehydrogenase kinase (PDK) activity. Our results show that these cells are quiescent cells expressing +4 ISCs and enteroendocrine markers. Active glycolysis in these cells suppresses ROS accumulation and enhances their stem cell and tumorigenic potential. Our studies reveal that aerobic glycolysis represents a heterogeneous feature of cancer, and indicate that this metabolic adaptation can occur in non-dividing cells, suggesting a role for the Warburg effect beyond biomass production in tumors.
    DOI:  https://doi.org/10.1038/s41467-022-29085-y
  9. Endocr Relat Cancer. 2022 Mar 01. pii: ERC-21-0349. [Epub ahead of print]
    A suppressor of dioxygenase inhibition in a yeast model of SDH deficiency.
    William Beimers, Megan Braun, Kaleb Schwinefus, Keenan Pearson, Brandon Wilbanks, Louis James Maher.
      A fascinating class of familial paraganglioma (PGL) neuroendocrine tumors is driven by loss of the tricarboxylic acid (TCA) cycle enzyme succinate dehydrogenase (SDH) resulting in succinate accumulation as an oncometabolite, and other metabolic derangements. Here we exploit a S. cerevisiae yeast model of SDH loss where accumulating succinate, and possibly reactive oxygen species, poison a dioxygenase enzyme required for sulfur scavenging. Using this model we performed a chemical suppression screen for compounds that relieve dioxygenase inhibition. After testing 1280 pharmaceutically-active compounds we identified meclofenoxate HCL, and its hydrolysis product, dimethylaminoethanol (DMAE), as suppressors of dioxygenase intoxication in SDH-loss yeast cells. We show that DMAE acts to alter metabolism so as to normalize the succinate:2-ketoglutarate ratio, improving dioxygenase function. This work raises the possibility that oncometabolite effects might be therapeutically suppressed by drugs that rewire metabolism to reduce the flux of carbon into pathological metabolic pathways.
    DOI:  https://doi.org/10.1530/ERC-21-0349
  10. Cancers (Basel). 2022 Mar 15. pii: 1504. [Epub ahead of print]14(6):
    Divergent Metabolic Effects of Metformin Merge to Enhance Eicosapentaenoic Acid Metabolism and Inhibit Ovarian Cancer In Vivo.
    Mary P Udumula, Laila M Poisson, Indrani Dutta, Nivedita Tiwari, Seongho Kim, Jasdeep Chinna-Shankar, Ghassan Allo, Sharif Sakr, Miriana Hijaz, Adnan R Munkarah, Shailendra Giri, Ramandeep Rattan.
      Metformin is being actively repurposed for the treatment of gynecologic malignancies including ovarian cancer. We investigated if metformin induces analogous metabolic changes across ovarian cancer cells. Functional metabolic analysis showed metformin caused an immediate and sustained decrease in oxygen consumption while increasing glycolysis across A2780, C200, and SKOV3ip cell lines. Untargeted metabolomics showed metformin to have differential effects on glycolysis and TCA cycle metabolites, while consistent increased fatty acid oxidation intermediates were observed across the three cell lines. Metabolite set enrichment analysis showed alpha-linolenic/linoleic acid metabolism as being most upregulated. Downstream mediators of the alpha-linolenic/linoleic acid metabolism, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were abundant in all three cell lines. EPA was more effective in inhibiting SKOV3 and CaOV3 xenografts, which correlated with inhibition of inflammatory markers and indicated a role for EPA-derived specialized pro-resolving mediators such as Resolvin E1. Thus, modulation of the metabolism of omega-3 fatty acids and their anti-inflammatory signaling molecules appears to be one of the common mechanisms of metformin's antitumor activity. The distinct metabolic signature of the tumors may indicate metformin response and aid the preclinical and clinical interpretation of metformin therapy in ovarian and other cancers.
    Keywords:  DHA; EPA; metabolomics; metformin; omega-3 fatty acids; ovarian cancer
    DOI:  https://doi.org/10.3390/cancers14061504
  11. Sichuan Da Xue Xue Bao Yi Xue Ban. 2022 Mar;53(2): 335-341
    [Cholesterol Metabolism and Tumor Immunity].
    Na Luo, Rong-Chen Shi, Rong-Yang Dai, Hong-Ming Miao.
      Cholesterol, an important lipid molecule of organisms, is involved in the formation of cell membrane structure, bile acid metabolism and steroid hormone synthesis, playing an important role in the regulation of cell structure and functions. In recent years, a large number of studies have shown that cholesterol metabolism is reprogrammed during tumor formation and development. In addition to directly affecting the biological behavior of tumor cells, cholesterol metabolic reprogramming also regulates the antitumor activity of immune cells in the tumor microenvironment. We reviewed herein the cholesterol metabolism reprogramming of and interactions among immune cells including myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), dendritic cells (DCs), and T cells in the tumor microenvironment. However, the relationship between cholesterol metabolism and tumor immunity in tumor microenvironment is complex and diversified. The differences and similarities of cholesterol metabolism reprogramming in tumor microenvironment in regulating immune cell activity and the specific regulatory mechanism are still unresolved issues. Targeted intervention of the cholesterol metabolism pathway of immune cells is expected to become a new strategy of cholesterol metabolism in tumor immunotherapy.
    Keywords:  Cholesterol; Immune regulation; Metabolism; Tumor; Tumor microenvironment
    DOI:  https://doi.org/10.12182/20220360202
  12. Cardiovasc Res. 2022 Mar 24. pii: cvac030. [Epub ahead of print]
    The regulation of cardiac intermediary metabolism by NADPH oxidases.
    Adam A Nabeebaccus, Christina M Reumiller, Jie Shen, Anna Zoccarato, Celio Xc Santos, Ajay M Shah.
      NADPH oxidase enzymes (NOXs), enzymes whose primary function is to generate reactive oxygen species, are important regulators of the heart's physiological function and response to pathological insults. The role of NOX-driven redox signalling in pathophysiological myocardial remodelling, including processes such as interstitial fibrosis, contractile dysfunction, cellular hypertrophy and cell survival, is well recognised. While the NOX2 isoform promotes many detrimental effects, the NOX4 isoform has attracted considerable attention as a driver of adaptive stress responses both during pathology and under physiological states such as exercise. Recent studies have begun to define some of the NOX4-modulated mechanisms that may underlie these adaptive responses. In particular, novel functions of NOX4 in driving cellular metabolic changes have emerged. Alterations in cellular metabolism are a recognised hallmark of the heart's response to physiological and pathological stresses. In this review, we highlight the emerging roles of NOX enzymes as important modulators of cellular intermediary metabolism in the heart, linking stress responses not only to myocardial energetics but also other functions. The novel interplay of NOX-modulated redox signalling pathways and intermediary metabolism in the heart is unravelling a new aspect of the fascinating biology of these enzymes which will inform better understanding of how they drive adaptative responses. We also discuss the implications of these new findings for therapeutic approaches that target metabolism in cardiac disease.
    Keywords:  NADPH oxidases; heart; intermediary metabolism; redox; signalling
    DOI:  https://doi.org/10.1093/cvr/cvac030
  13. Front Nutr. 2022 ;9 809485
    Chronic Lactate Exposure Decreases Mitochondrial Function by Inhibition of Fatty Acid Uptake and Cardiolipin Alterations in Neonatal Rat Cardiomyocytes.
    Iñigo San-Millan, Genevieve C Sparagna, Hailey L Chapman, Valerie L Warkins, Kathryn C Chatfield, Sydney R Shuff, Janel L Martinez, George A Brooks.
       Introduction: Lactate is an important signaling molecule with autocrine, paracrine and endocrine properties involved in multiple biological processes including regulation of gene expression and metabolism. Levels of lactate are increased chronically in diseases associated with cardiometabolic disease such as heart failure, type 2 diabetes, and cancer. Using neonatal ventricular myocytes, we tested the hypothesis that chronic lactate exposure could decrease the activity of cardiac mitochondria that could lead to metabolic inflexibility in the heart and other tissues.
    Methods: Neonatal rat ventricular myocytes (NRVMs) were treated for 48 h with 5, 10, or 20 mM lactate and CPT I and II activities were tested using radiolabelled assays. The molecular species profile of the major mitochondrial phospholipid, cardiolipin, was determined using electrospray ionization mass spectrometry along with reactive oxygen species (ROS) levels measured by Amplex Red and mitochondrial oxygen consumption using the Seahorse analyzer.
    Results: CPT I activity trended downward (p = 0.07) and CPT II activity significantly decreased with lactate exposure (p < 0.001). Cardiolipin molecular species containing four 18 carbon chains (72 carbons total) increased with lactate exposure, but species of other sizes decreased significantly. Furthermore, ROS production was strongly enhanced with lactate (p < 0.001) and mitochondrial ATP production and maximal respiration were both significantly down regulated with lactate exposure (p < 0.05 and p < 0.01 respectively).
    Conclusions: Chronic lactate exposure in cardiomyocytes leads to a decrease in fatty acid transport, alterations of cardiolipin remodeling, increases in ROS production and decreases in mitochondrial oxygen consumption that could have implications for both metabolic health and flexibility. The possibility that both intra-, or extracellular lactate levels play roles in cardiometabolic disease, heart failure, and other forms of metabolic inflexibility needs to be assessed in vivo.
    Keywords:  fatty acid metabolism; fatty acids transport; lactate; metabolic flexibility; mitochondrial dysfunction
    DOI:  https://doi.org/10.3389/fnut.2022.809485
  14. Cancers (Basel). 2022 Mar 10. pii: 1433. [Epub ahead of print]14(6):
    The Interplay between Cell-Extracellular Matrix Interaction and Mitochondria Dynamics in Cancer.
    Bian Yanes, Elena Rainero.
      The tumor microenvironment, in particular the extracellular matrix (ECM), plays a pivotal role in controlling tumor initiation and progression. In particular, the interaction between cancer cells and the ECM promotes cancer cell growth and invasion, leading to the formation of distant metastasis. Alterations in cancer cell metabolism is a key hallmark of cancer, which is often associated with alterations in mitochondrial dynamics. Recent research highlighted that, changes in mitochondrial dynamics are associated with cancer migration and metastasis-these has been extensively reviewed elsewhere. However, less is known about the interplay between the extracellular matrix and mitochondria functions. In this review, we will highlight how ECM remodeling associated with tumorigenesis contribute to the regulation of mitochondrial function, ultimately promoting cancer cell metabolic plasticity, able to fuel cancer invasion and metastasis.
    Keywords:  extracellular matrix; mitochondria dynamics; tumor microenvironment
    DOI:  https://doi.org/10.3390/cancers14061433
  15. Cell Metab. 2022 Mar 15. pii: S1550-4131(22)00087-0. [Epub ahead of print]
    The glucose transporter GLUT3 controls T helper 17 cell responses through glycolytic-epigenetic reprogramming.
    Sophia M Hochrein, Hao Wu, Miriam Eckstein, Laura Arrigoni, Josip S Herman, Fabian Schumacher, Christian Gerecke, Mathias Rosenfeldt, Dominic Grün, Burkhard Kleuser, Georg Gasteiger, Wolfgang Kastenmüller, Bart Ghesquière, Jan Van den Bossche, E Dale Abel, Martin Vaeth.
      Metabolic reprogramming is a hallmark of activated T cells. The switch from oxidative phosphorylation to aerobic glycolysis provides energy and intermediary metabolites for the biosynthesis of macromolecules to support clonal expansion and effector function. Here, we show that glycolytic reprogramming additionally controls inflammatory gene expression via epigenetic remodeling. We found that the glucose transporter GLUT3 is essential for the effector functions of Th17 cells in models of autoimmune colitis and encephalomyelitis. At the molecular level, we show that GLUT3-dependent glucose uptake controls a metabolic-transcriptional circuit that regulates the pathogenicity of Th17 cells. Metabolomic, epigenetic, and transcriptomic analyses linked GLUT3 to mitochondrial glucose oxidation and ACLY-dependent acetyl-CoA generation as a rate-limiting step in the epigenetic regulation of inflammatory gene expression. Our findings are also important from a translational perspective because inhibiting GLUT3-dependent acetyl-CoA generation is a promising metabolic checkpoint to mitigate Th17-cell-mediated inflammatory diseases.
    Keywords:  ACLY; ATP-citrate lyase; GLUT1; GLUT3; Th17 cells; acetyl-CoA; glucose metabolism; glycolysis; histone acetylation; immunometabolism
    DOI:  https://doi.org/10.1016/j.cmet.2022.02.015
  16. Adv Sci (Weinh). 2022 Mar 23. e2105437
    Towards Mapping Mouse Metabolic Tissue Atlas by Mid-Infrared Imaging with Heavy Water Labeling.
    Xinwen Liu, Lixue Shi, Lingyan Shi, Mian Wei, Zhilun Zhao, Wei Min.
      Understanding metabolism is of great significance to decipher various physiological and pathogenic processes. While great progress has been made to profile gene expression, how to capture organ-, tissue-, and cell-type-specific metabolic profile (i.e., metabolic tissue atlas) in complex mammalian systems is lagging behind, largely owing to the lack of metabolic imaging tools with high resolution and high throughput. Here, the authors applied mid-infrared imaging coupled with heavy water (D2 O) metabolic labeling to a scope of mouse organs and tissues. The premise is that, as D2 O participates in the biosynthesis of various macromolecules, the resulting broad C-D vibrational spectrum should interrogate a wide range of metabolic pathways. Applying multivariate analysis to the C-D spectrum, the authors successfully identified both inter-organ and intra-tissue metabolic signatures of mice. A large-scale metabolic atlas map between different organs from the same mice is thus generated. Moreover, leveraging the power of unsupervised clustering methods, spatially-resolved metabolic signatures of brain tissues are discovered, revealing tissue and cell-type specific metabolic profile in situ. As a demonstration of this technique, the authors captured metabolic changes during brain development and charaztereized intratumoral metabolic heterogeneity of glioblastoma. Altogether, the integrated platform paves a way to map the metabolic tissue atlas for complex mammalian systems.
    Keywords:  heavy water labeling; infrared imaging; metabolic heterogeneity; metabolism; multivariate analysis
    DOI:  https://doi.org/10.1002/advs.202105437
  17. Front Oncol. 2022 ;12 802807
    Thymidine Kinase 1 Drives Skin Cutaneous Melanoma Malignant Progression and Metabolic Reprogramming.
    Sipeng Zuo, Huixue Wang, Lin Li, Hui Pan, Linna Lu.
       Background: Thymidine kinase 1 (TK1) is a cell cycle-dependent kinase that catalyzes the addition of a gamma-phosphate group to thymidine. The protumorigenic role of TK1 has been reported in various malignancies. However, the role of TK1 in skin cutaneous melanoma (SKCM) remains unclear. This study aimed to explore the molecular function of TK1 in SKCM progression.
    Methods: Bioinformatics data were acquired from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). Subcutaneous xenografts were established to observe the effect of TK1 knockdown on the proliferation of SKCM cells in vivo. RNA sequencing (RNA-seq; deposited in Sequence Read Archive, SRX10950283-SRX10950285 for A375 control cells and SRX10950286-SRX10950288 for TK1-silenced A375 cells) and immunoprecipitation-mass spectrometry (IP-MS) were used to analyze TK1-related genes and pathways. Seahorse XF Cell Mito tests and glycolysis stress assays were conducted for metabolic testing.
    Results: TK1 was upregulated in malignant SKCM compared to that in normal tissues and cell lines. Elevated expression of TK1 was associated with poor prognosis. In vitro and in vivo assays demonstrated that TK1 promoted the proliferation and migration of SKCM cells. Moreover, TK1 was strongly associated with multiple intracellular metabolic pathways, facilitating cell mitochondrial respiration and glycolysis in SKCM malignant progression.
    Conclusions: TK1 drives SKCM malignant progression and supports metabolic reprogramming, indicating that TK1 serves as a therapeutic target for SKCM.
    Keywords:  bioinformatics; cell metabolism; skin cutaneous melanoma; thymidine kinase 1; tumorigenesis
    DOI:  https://doi.org/10.3389/fonc.2022.802807
  18. Metabolites. 2022 Mar 21. pii: 267. [Epub ahead of print]12(3):
    Untargeted Metabolomics Showed Accumulation of One-Carbon Metabolites to Facilitate DNA Methylation during Extracellular Matrix Detachment of Cancer Cells.
    Suza Mohammad Nur, Mohammed Razeeth Shait Mohammed, Mazin A Zamzami, Hani Choudhry, Aamir Ahmad, Bushra Ateeq, Irfan A Rather, Mohammad Imran Khan.
      Tumor cells detached from the extracellular matrix (ECM) undergo anoikis resistance and metabolic reprogramming to facilitate cancer cell survival and promote metastasis. During ECM detachment, cancer cells utilize genomic methylation to regulate transcriptional events. One-carbon (1C) metabolism is a well-known contributor of SAM, a global substrate for methylation reactions, especially DNA methylation. DNA methylation-mediated repression of NK cell ligands MICA and MICB during ECM detachment has been overlooked. In the current work, we quantitated the impact of ECM detachment on one-carbon metabolites, expression of 1C regulatory pathway genes, and total methylation levels. Our results showed that ECM detachment promotes the accumulation of one-carbon metabolites and induces regulatory pathway genes and total DNA methylation. Furthermore, we measured the expression of well-known targets of DNA methylation in NK cell ligands in cancer cells, namely, MICA/B, during ECM detachment and observed low expression compared to ECM-attached cancer cells. Finally, we treated the ECM-detached cancer cells with vitamin C (a global methylation inhibitor) and observed a reduction in the promoter methylation of NK cell ligands, resulting in MICA/B re-expression. Treatment with vitamin C was also found to reduce global DNA methylation levels in ECM-detached cancer cells.
    Keywords:  DNA methylation; ECM detachment; NKG2DLs; anoikis; one-carbon metabolism
    DOI:  https://doi.org/10.3390/metabo12030267
  19. Antioxidants (Basel). 2022 Feb 25. pii: 461. [Epub ahead of print]11(3):
    Venetoclax-Resistant MV4-11 Leukemic Cells Activate PI3K/AKT Pathway for Metabolic Reprogramming and Redox Adaptation for Survival.
    Hind A Alkhatabi, Samir F Zohny, Mohammed Razeeth Shait Mohammed, Hani Choudhry, Mohd Rehan, Aamir Ahmad, Farid Ahmed, Mohammad Imran Khan.
      Venetoclax (ABT199) is a selective B-cell lymphoma 2 (BCL-2) inhibitor. The US FDA recently approved it to be used in combination with low-dose cytarabine or hypomethylating agents in acute myeloid leukemia (AML) or elderly patients non-eligible for chemotherapy. However, acquiring resistance to venetoclax in AML patients is the primary cause of treatment failure. To understand the molecular mechanisms inherent in the resistance to BCL-2 inhibitors, we generated a venetoclax-resistant cell line model and assessed the consequences of this resistance on its metabolic pathways. Untargeted metabolomics data displayed a notable impact of resistance on the PI3K/AKT pathway, the Warburg effect, glycolysis, the TCA cycle, and redox metabolism. The resistant cells showed increased NADPH and reduced glutathione levels, switching their energy metabolism towards glycolysis. PI3K/AKT pathway inhibition shifted resistant cells towards oxidative phosphorylation (OXPHOS). Our results provide a metabolic map of resistant cells that can be used to design novel metabolic targets to challenge venetoclax resistance in AML.
    Keywords:  MV4-11; OXPHOS; PI3K/AKT pathway; acute myeloid leukemia; glycolysis; metabolomics; redox metabolism; venetoclax; venetoclax resistance model
    DOI:  https://doi.org/10.3390/antiox11030461
  20. Metabolites. 2022 Feb 24. pii: 203. [Epub ahead of print]12(3):
    Maternal Nutrient Restriction Disrupts Gene Expression and Metabolites Associated with Urea Cycle, Steroid Synthesis, Glucose Homeostasis, and Glucuronidation in Fetal Calf Liver.
    Susumu Muroya, Yi Zhang, Kounosuke Otomaru, Kazunaga Oshima, Ichiro Oshima, Mitsue Sano, Sanggun Roh, Koichi Ojima, Takafumi Gotoh.
      This study aimed to understand the mechanisms underlying the effects of maternal undernutrition (MUN) on liver growth and metabolism in Japanese Black fetal calves (8.5 months in utero) using an approach that integrates metabolomics and transcriptomics. Dams were fed 60% (low-nutrition; LN) or 120% (high-nutrition; HN) of their overall nutritional requirements during gestation. We found that MUN markedly decreased the body and liver weights of the fetuses; metabolomic analysis revealed that aspartate, glycerol, alanine, gluconate 6-phosphate, and ophthalmate levels were decreased, whereas UDP-glucose, UDP-glucuronate, octanoate, and 2-hydroxybutyrate levels were decreased in the LN fetal liver (p ≤ 0.05). According to metabolite set enrichment analysis, the highly different metabolites were associated with metabolisms including the arginine and proline metabolism, nucleotide and sugar metabolism, propanoate metabolism, glutamate metabolism, porphyrin metabolism, and urea cycle. Transcriptomic and qPCR analyses revealed that MUN upregulated QRFPR and downregulated genes associated with the glucose homeostasis (G6PC, PCK1, DPP4), ketogenesis (HMGCS2), glucuronidation (UGT1A1, UGT1A6, UGT2A1), lipid metabolism (ANGPTL4, APOA5, FADS2), cholesterol and steroid homeostasis (FDPS, HSD11B1, HSD17B6), and urea cycle (CPS1, ASS1, ASL, ARG2). These metabolic pathways were extracted as relevant terms in subsequent gene ontology/pathway analyses. Collectively, these results indicate that the citrate cycle was maintained at the expense of activities of the energy metabolism, glucuronidation, steroid hormone homeostasis, and urea cycle in the liver of MUN fetuses.
    Keywords:  fetal growth restriction (fgr); fetal programming; glucuronidation; liver; maternal nutrient restriction; steroid synthesis; urea cycle
    DOI:  https://doi.org/10.3390/metabo12030203
  21. Int J Mol Sci. 2022 Mar 09. pii: 2949. [Epub ahead of print]23(6):
    Polyunsaturated Fatty Acid-Enriched Lipid Fingerprint of Glioblastoma Proliferative Regions Is Differentially Regulated According to Glioblastoma Molecular Subtype.
    Albert Maimó-Barceló, Lucía Martín-Saiz, José A Fernández, Karim Pérez-Romero, Santiago Garfias-Arjona, Mónica Lara-Almúnia, Javier Piérola-Lopetegui, Joan Bestard-Escalas, Gwendolyn Barceló-Coblijn.
      Glioblastoma (GBM) represents one of the deadliest tumors owing to a lack of effective treatments. The adverse outcomes are worsened by high rates of treatment discontinuation, caused by the severe side effects of temozolomide (TMZ), the reference treatment. Therefore, understanding TMZ's effects on GBM and healthy brain tissue could reveal new approaches to address chemotherapy side effects. In this context, we have previously demonstrated the membrane lipidome is highly cell type-specific and very sensitive to pathophysiological states. However, little remains known as to how membrane lipids participate in GBM onset and progression. Hence, we employed an ex vivo model to assess the impact of TMZ treatment on healthy and GBM lipidome, which was established through imaging mass spectrometry techniques. This approach revealed that bioactive lipid metabolic hubs (phosphatidylinositol and phosphatidylethanolamine plasmalogen species) were altered in healthy brain tissue treated with TMZ. To better understand these changes, we interrogated RNA expression and DNA methylation datasets of the Cancer Genome Atlas database. The results enabled GBM subtypes and patient survival to be linked with the expression of enzymes accounting for the observed lipidome, thus proving that exploring the lipid changes could reveal promising therapeutic approaches for GBM, and ways to ameliorate TMZ side effects.
    Keywords:  MALDI-IMS lipidomics; glioblastoma; lipid metabolism; modular gene expression; molecular subtypes; temozolomide
    DOI:  https://doi.org/10.3390/ijms23062949
  22. Immunology. 2022 Mar 23.
    1,25-dihydroxyvitamin D3 suppresses CD4+ T cell effector functionality by inhibition of glycolysis.
    E L Bishop, N Gudgeon, G Mackie, D Chauss, J Roberts, D A Tennant, K M Maslowski, B Afzali, M Hewison, S Dimeloe.
      In CD4+ T helper cells, the active form of vitamin D3 , 1,25-dihydroxyvitamin D3 (1,25D) suppresses production of inflammatory cytokines, including interferon-gamma (IFN-γ), but the mechanisms for this are not yet fully defined. In innate immune cells, response to 1,25D has been linked to metabolic reprogramming. It is unclear whether 1,25D has similar effects on CD4+ T cells, although it is known that antigen stimulation of these cells promotes an anabolic metabolic phenotype, characterised by high rates of aerobic glycolysis to support clonal expansion and effector cytokine expression. Here, we performed in-depth analysis of metabolic capacity and pathway usage, employing extracellular flux and stable isotope-based tracing approaches, in CD4+ T cells treated with 1,25D. We report that 1,25D significantly decreases rates of aerobic glycolysis in activated CD4+ T cells, whilst exerting a lesser effect on mitochondrial glucose oxidation. This is associated with transcriptional repression of Myc, but not repression of mTOR activity under these conditions. Consistent with the modest effect of 1,25D on mitochondrial activity, it also did not impact CD4+ T cell mitochondrial mass or membrane potential. Finally, we demonstrate that inhibition of aerobic glycolysis by 1,25D substantially contributes to its immune-regulatory capacity in CD4+ T cells, since the suppression of IFN-γ expression was significantly blunted in the absence of aerobic glycolysis. This article is protected by copyright. All rights reserved.
    Keywords:  T cell; glycolysis; immunometabolism; metabolism; vitamin D
    DOI:  https://doi.org/10.1111/imm.13472
  23. Front Cell Dev Biol. 2022 ;10 871471
    Editorial: Metabolism and Cell Adhesion in Cancer.
    Tanja Nicole Hartmann.
      
    Keywords:  AMPK; FAK; adhesion; integrin; mTOR; metabolism; migration; tumor microenvironment
    DOI:  https://doi.org/10.3389/fcell.2022.871471
  24. Cancers (Basel). 2022 Mar 10. pii: 1438. [Epub ahead of print]14(6):
    The Matrisome Is Associated with Metabolic Reprograming in Stem-like Phenotypes of Gastric Cancer.
    Ji-Yong Sung, Jae-Ho Cheong.
      The extracellular matrix (ECM) is an important regulator of all cellular functions, and the matrisome represents a major component of the tumor microenvironment. The matrisome is an essential component comprising genes encoding ECM glycoproteins, collagens, and proteoglycans; however, its role in cancer progression and the development of stem-like molecular subtypes in gastric cancer is unknown. We analyzed gastric cancer data from five molecular subtypes (n = 497) and found that metabolic reprograming differs based on the state of the matrisome. Approximately 95% of stem-like cancer type samples of gastric cancer were in the high-matrisome category, and energy metabolism was considerably increased in the high-matrisome group. Particularly, high glycosaminoglycan biosynthesis-chondroitin sulfate metabolic reprograming was associated with an unfavorable prognosis. Glycosaminoglycan biosynthesis-chondroitin sulfate metabolic reprograming may occur according to the matrisome status and contribute to the development of stem-like phenotypes. Our analysis suggests the possibility of precision medicine for anticancer therapies.
    Keywords:  epithelial-mesenchymal transition; extracellular matrix; glycosaminoglycan biosynthesis-chondroitin sulfate; matrisome; stem-like gastric cancer
    DOI:  https://doi.org/10.3390/cancers14061438
  25. Cancer Cell. 2022 Mar 15. pii: S1535-6108(22)00118-0. [Epub ahead of print]
    CD8+ T cells PUF(A)ing the flames of cancer ferroptotic cell death.
    José Pedro Friedmann Angeli, Thamara Nishida Xavier da Silva, Bastian Schilling.
      In this issue of Cancer Cell, Liao et al. demonstrate that CD8+ T cell-secreted interferon-gamma (IFN-γ) rewires cancer cell lipid metabolism via the enzyme acyl-CoA synthetase long-chain family member 4 (ACSL4). ACSL4 activates polyunsaturated fatty acids and sensitizes cancer cells to ferroptosis in immunotherapy-relevant settings. These findings provide insights into how the metabolic and immune milieu could be used to promote ferroptosis.
    DOI:  https://doi.org/10.1016/j.ccell.2022.03.003
  26. Int J Mol Sci. 2022 Mar 17. pii: 3266. [Epub ahead of print]23(6):
    Differential Metabotypes in Synovial Fibroblasts and Synovial Fluid in Hip Osteoarthritis Patients Support Inflammatory Responses.
    Hussein Farah, Susanne N Wijesinghe, Thomas Nicholson, Fawzeyah Alnajjar, Michelangelo Certo, Abdullah Alghamdi, Edward T Davis, Stephen P Young, Claudio Mauro, Simon W Jones.
      Changes in cellular metabolism have been implicated in mediating the activated fibroblast phenotype in a number of chronic inflammatory disorders, including pulmonary fibrosis, renal disease and rheumatoid arthritis. The aim of this study was therefore to characterise the metabolic profile of synovial joint fluid and synovial fibroblasts under both basal and inflammatory conditions in a cohort of obese and normal-weight hip OA patients. Furthermore, we sought to ascertain whether modulation of a metabolic pathway in OA synovial fibroblasts could alter their inflammatory activity. Synovium and synovial fluid was obtained from hip OA patients, who were either of normal-weight or obese and were undergoing elective joint replacement surgery. The synovial fluid metabolome was determined by 1H NMR spectroscopy. The metabolic profile of isolated synovial fibroblasts in vitro was characterised by lactate secretion, oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) using the Seahorse XF Analyser. The effects of a small molecule pharmacological inhibitor and siRNA targeted at glutaminase-1 (GLS1) were assessed to probe the role of glutamine metabolism in OA synovial fibroblast function. Obese OA patient synovial fluid (n = 5) exhibited a different metabotype, compared to normal-weight patient fluid (n = 6), with significantly increased levels of 1, 3-dimethylurate, N-Nitrosodimethylamine, succinate, tyrosine, pyruvate, glucose, glycine and lactate, and enrichment of the glutamine-glutamate metabolic pathway, which correlated with increasing adiposity. In vitro, isolated obese OA fibroblasts exhibited greater basal lactate secretion and aerobic glycolysis, and increased mitochondrial respiration when stimulated with pro-inflammatory cytokine TNFα, compared to fibroblasts from normal-weight patients. Inhibition of GLS1 attenuated the TNFα-induced expression and secretion of IL-6 in OA synovial fibroblasts. These findings suggest that altered cellular metabolism underpins the inflammatory phenotype of OA fibroblasts, and that targeted inhibition of glutamine-glutamate metabolism may provide a route to reducing the pathological effects of joint inflammation in OA patients who are obese.
    Keywords:  IL6; glutamine; inflammation; metabolism; osteoarthritis; synovial fibroblast
    DOI:  https://doi.org/10.3390/ijms23063266
  27. Int J Mol Sci. 2022 Mar 15. pii: 3162. [Epub ahead of print]23(6):
    Metabolic Response in Endothelial Cells to Catecholamine Stimulation Associated with Increased Vascular Permeability.
    Adrián López García de Lomana, Arnar Ingi Vilhjálmsson, Sarah McGarrity, Rósa Sigurðardóttir, Ósk Anuforo, Alexía Rós Viktorsdóttir, Aris Kotronoulas, Andreas Bergmann, Leifur Franzson, Haraldur Halldórsson, Hanne H Henriksen, Charles E Wade, Pär Ingemar Johansson, Óttar Rolfsson.
      Disruption to endothelial cell homeostasis results in an extensive variety of human pathologies that are particularly relevant to major trauma. Circulating catecholamines, such as adrenaline and noradrenaline, activate endothelial adrenergic receptors triggering a potent response in endothelial function. The regulation of the endothelial cell metabolism is distinct and profoundly important to endothelium homeostasis. However, a precise catalogue of the metabolic alterations caused by sustained high catecholamine levels that results in endothelial dysfunction is still underexplored. Here, we uncover a set of up to 46 metabolites that exhibit a dose-response relationship to adrenaline-noradrenaline equimolar treatment. The identified metabolites align with the glutathione-ascorbate cycle and the nitric oxide biosynthesis pathway. Certain key metabolites, such as arginine and reduced glutathione, displayed a differential response to treatment in early (4 h) compared to late (24 h) stages of sustained stimulation, indicative of homeostatic metabolic feedback loops. Furthermore, we quantified an increase in the glucose consumption and aerobic respiration in endothelial cells upon catecholamine stimulation. Our results indicate that oxidative stress and nitric oxide metabolic pathways are downstream consequences of endothelial cell stimulation with sustained high levels of catecholamines. A precise understanding of the metabolic response in endothelial cells to pathological levels of catecholamines will facilitate the identification of more efficient clinical interventions in trauma patients.
    Keywords:  catecholamines; endotheliopathy; major trauma; metabolomics; vascular permeability
    DOI:  https://doi.org/10.3390/ijms23063162
  28. Front Cell Infect Microbiol. 2022 ;12 854241
    Editorial: The Role of Systemic and Cellular Metabolism on Susceptibility to Infections and Responsiveness to Vaccination.
    Antonella Caputo, Carlos A Guzman, Clovis S Palmer, Francesco Nicoli.
      
    Keywords:  bacteria; cellular metabolism; immunometabolism; metabolic disorder; non-communicable diseases; pathogen; virus
    DOI:  https://doi.org/10.3389/fcimb.2022.854241
  29. Metabolites. 2022 Mar 21. pii: 270. [Epub ahead of print]12(3):
    Mitochondrial Respiration in Response to Iron Deficiency Anemia: Comparison of Peripheral Blood Mononuclear Cells and Liver.
    Christine Fischer, Lara Valente de Souza, Timea Komlódi, Luiz F Garcia-Souza, Chiara Volani, Piotr Tymoszuk, Egon Demetz, Markus Seifert, Kristina Auer, Richard Hilbe, Natascha Brigo, Verena Petzer, Malte Asshoff, Erich Gnaiger, Günter Weiss.
      Iron is an essential component for metabolic processes, including oxygen transport within hemoglobin, tricarboxylic acid (TCA) cycle activity, and mitochondrial energy transformation. Iron deficiency can thus lead to metabolic dysfunction and eventually result in iron deficiency anemia (IDA), which affects approximately 1.5 billion people worldwide. Using a rat model of IDA induced by phlebotomy, we studied the effects of IDA on mitochondrial respiration in peripheral blood mononuclear cells (PBMCs) and the liver. Furthermore, we evaluated whether the mitochondrial function evaluated by high-resolution respirometry in PBMCs reflects corresponding alterations in the liver. Surprisingly, mitochondrial respiratory capacity was increased in PBMCs from rats with IDA compared to the controls. In contrast, mitochondrial respiration remained unaffected in livers from IDA rats. Of note, citrate synthase activity indicated an increased mitochondrial density in PBMCs, whereas it remained unchanged in the liver, partly explaining the different responses of mitochondrial respiration in PBMCs and the liver. Taken together, these results indicate that mitochondrial function determined in PBMCs cannot serve as a valid surrogate for respiration in the liver. Metabolic adaptions to iron deficiency resulted in different metabolic reprogramming in the blood cells and liver tissue.
    Keywords:  OXPHOS; anemia; iron deficiency; liver; mitochondrial function; mitochondrial respiration; peripheral blood mononuclear cells; surrogate
    DOI:  https://doi.org/10.3390/metabo12030270
  30. Zhonghua Zhong Liu Za Zhi. 2022 Mar 23. 44(3): 252-259
    [Urine metabolomics study of hepatocellular carcinoma].
    X F Xie, Y Sun, X H Zhao.
      Objective: To investigate the urinary small molecular metabolites and their metabolic characteristics of patients with hepatocellular carcinoma (HCC). Methods: High throughput ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was used to detect the small molecular metabolites in urine of healthy control (n=10), patients with hepatic hemangioma (n=10) and patients with HCC (n=10). The orthogonal projections to latent structures-discriminant analysis (OPLS-DA), hierarchical cluster analysis of multivariate analysis and univariate analysis were used to analyze the differential metabolites of the three groups. Results: The metabolic profiles of the three groups showed that the total of 381 differential metabolites were identified and divided into 96 up-regulated metabolites and 285 down-regulated metabolites. There were 55 urinary metabolites specifically related to HCC. Twenty-one of them were significantly up-regulated, including Acetyl-DL-Leucine, Ala Asp, HoPhe-Gly-OH, while 34 were significantly down-regulated, including Selenocystathionine, Met Trp Met Cys, Valsartan acid and so on. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the differential metabolites were mainly enriched in glutamine/glutamate metabolism, lysine biosynthesis, tricarboxylic acid cycle and purine metabolism. Conclusions: The occurrence of HCC is accompanied by the abnormalities of multiple metabolites and metabolic pathways. The analysis of the characteristic metabolic profile of urine in patients with HCC is helpful to find metabolic markers and potential therapeutic targets for liver cancer.
    Keywords:  Biomarker; Hepatocellular neoplasms; Non-invasive diagnosis; Urinary metabolism
    DOI:  https://doi.org/10.3760/cma.j.cn112152-20200825-00765
  31. Biomolecules. 2022 Mar 10. pii: 427. [Epub ahead of print]12(3):
    Nuclear-Mitochondrial Interactions.
    Brittni R Walker, Carlos T Moraes.
      Mitochondria, the cell's major energy producers, also act as signaling hubs, interacting with other organelles both directly and indirectly. Despite having its own circular genome, the majority of mitochondrial proteins are encoded by nuclear DNA. To respond to changes in cell physiology, the mitochondria must send signals to the nucleus, which can, in turn, upregulate gene expression to alter metabolism or initiate a stress response. This is known as retrograde signaling. A variety of stimuli and pathways fall under the retrograde signaling umbrella. Mitochondrial dysfunction has already been shown to have severe implications for human health. Disruption of retrograde signaling, whether directly associated with mitochondrial dysfunction or cellular environmental changes, may also contribute to pathological deficits. In this review, we discuss known signaling pathways between the mitochondria and the nucleus, examine the possibility of direct contacts, and identify pathological consequences of an altered relationship.
    Keywords:  MAMs; integrated stress response; mitochondria; nucleus; retrograde signaling
    DOI:  https://doi.org/10.3390/biom12030427
  32. Mol Cell Biochem. 2022 Mar 25.
    NAD+ centric mechanisms and molecular determinants of skeletal muscle disease and aging.
    Sabrina Wagner, Ravikumar Manickam, Marco Brotto, Srinivas M Tipparaju.
      The nicotinamide adenine dinucleotide (NAD+) is an essential redox cofactor, involved in various physiological and molecular processes, including energy metabolism, epigenetics, aging, and metabolic diseases. NAD+ repletion ameliorates muscular dystrophy and improves the mitochondrial and muscle stem cell function and thereby increase lifespan in mice. Accordingly, NAD+ is considered as an anti-oxidant and anti-aging molecule. NAD+ plays a central role in energy metabolism and the energy produced is used for movements, thermoregulation, and defense against foreign bodies. The dietary precursors of NAD+ synthesis is targeted to improve NAD+ biosynthesis; however, studies have revealed conflicting results regarding skeletal muscle-specific effects. Recent advances in the activation of nicotinamide phosphoribosyltransferase in the NAD+ salvage pathway and supplementation of NAD+ precursors have led to beneficial effects in skeletal muscle pathophysiology and function during aging and associated metabolic diseases. NAD+ is also involved in the epigenetic regulation and post-translational modifications of proteins that are involved in various cellular processes to maintain tissue homeostasis. This review provides detailed insights into the roles of NAD+ along with molecular mechanisms during aging and disease conditions, such as the impacts of age-related NAD+ deficiencies on NAD+-dependent enzymes, including poly (ADP-ribose) polymerase (PARPs), CD38, and sirtuins within skeletal muscle, and the most recent studies on the potential of nutritional supplementation and distinct modes of exercise to replenish the NAD+ pool.
    Keywords:  Aging; Diabetes; Epigenetics; Muscle diseases; NAD+; Redox
    DOI:  https://doi.org/10.1007/s11010-022-04408-1
  33. Nutrients. 2022 Mar 12. pii: 1201. [Epub ahead of print]14(6):
    Distinct Effects of High-Fat and High-Phosphate Diet on Glucose Metabolism and the Response to Voluntary Exercise in Male Mice.
    Pablo Vidal, Lisa A Baer, Elisa Félix-Soriano, Felix T Yang, Daniel A Branch, Kedryn K Baskin, Kristin I Stanford.
      The prevalence of metabolic diseases is rapidly increasing and a principal contributor to this is diet, including increased consumption of energy-rich foods and foods with added phosphates. Exercise is an effective therapeutic approach to combat metabolic disease. While exercise is effective to combat the detrimental effects of a high-fat diet on metabolic health, the effects of exercise on a high-phosphate diet have not been thoroughly investigated. Here, we investigated the effects of a high-fat or high-phosphate diet in the presence or absence of voluntary exercise on metabolic function in male mice. To do this, mice were fed a low-fat, normal-phosphate diet (LFPD), a high-phosphate diet (HPD) or a high-fat diet (HFD) for 6 weeks and then subdivided into either sedentary or exercised (housed with running wheels) for an additional 8 weeks. An HFD severely impaired metabolic function in mice, increasing total fat mass and worsening whole-body glucose tolerance, while HPD did not induce any notable effects on glucose metabolism. Exercise reverted most of the detrimental metabolic adaptations induced by HFD, decreasing total fat mass and restoring whole-body glucose tolerance and insulin sensitivity. Interestingly, voluntary exercise had a similar effect on LFPD and HPD mice. These data suggest that a high-phosphate diet does not significantly impair glucose metabolism in sedentary or voluntary exercised conditions.
    Keywords:  adipose tissue; exercise; high-fat diet; high-phosphate diet; metabolism
    DOI:  https://doi.org/10.3390/nu14061201
  34. Stem Cells. 2022 Jan 24. pii: sxab022. [Epub ahead of print]
    Lactate Enhances Mouse ES Cell Differentiation Toward XEN Cells In Vitro.
    Mohamed I Gatie, Tyler T Cooper, Reza Khazaee, Gilles A Lajoie, Gregory M Kelly.
      Metabolism plays a crucial role for cell survival and function; however, recent evidence has implicated it in regulating embryonic development. In the embryo, the inner cell mass undergoes orchestrated cellular divisions resulting in the formation of pluripotent epiblast stem cells and primitive endoderm cells. However, both lineages can be captured in vitro as embryonic stem (ES) cells and extraembryonic endoderm (XEN) cells. Concomitantly, changes in the metabolic profile occurs during development, and are well documented in the embryonic lineages. However, a comprehensive multi-omic analysis of these features in XEN cells remains lacking. We observed that mouse XEN cells exhibited high sensitivity to glycolytic inhibition in addition to maintaining elevated intra- and extracellular lactate levels in vitro. Extraembryonic endoderm cells maintain high lactate levels by increased LDHA activity, and re-routing pyruvate away from the mitochondria resulting in reduced mitochondrial activity due to disruptions in electron transport chain stoichiometry. Importantly, exogenous lactate supplementation or promoting intracellular lactate accumulation enhances XEN differentiation in vitro. These results highlight how lactate contributes to XEN differentiation in vitro and may serve to enhance reprogramming efficiency of cells used for regenerative medicine.
    Keywords:  differentiation; embryonic stem cells; extraembryonic endoderm cells; glucose metabolism; lactate; pluripotency
    DOI:  https://doi.org/10.1093/stmcls/sxab022
  35. Int J Mol Sci. 2022 Mar 16. pii: 3219. [Epub ahead of print]23(6):
    Evaluation of Metabolic Changes in Acute Intermittent Porphyria Patients by Targeted Metabolomics.
    Alex Gomez-Gomez, Paula Aguilera, Klaus Langohr, Gregori Casals, Cristina Pavon, Josep Marcos, Jordi To-Figueras, Oscar J Pozo.
      Acute intermittent porphyria (AIP) is an inherited rare hepatic disorder due to mutations within the hydroxymethylbilane gene. AIP patients with active disease overproduce aminolevulinic acid (ALA) and porphobilinogen (PBG) in the liver which are exported inducing severe neurological attacks. Different hepatic metabolic abnormalities have been described to be associated with this condition. The goal of this research was to explore the metabolome of symptomatic AIP patients by state-of-the art liquid chromatography-tandem mass spectrometry (LC-MS/MS). A case versus control study including 18 symptomatic AIP patients and 33 healthy controls was performed. Plasmatic levels of 51 metabolites and 16 ratios belonging to four metabolic pathways were determined. The results showed that the AIP patients presented significant changes in the two main areas of the metabolome under study: (a) the tryptophan/kynurenine pathway with an increase of tryptophan in plasma together with increase of the kynurenine/tryptophan ratio; and (b) changes in the tricarboxylic acid cycle (TCA) including increase of succinic acid and decrease of the fumaric acid/succinic acid ratio. We performed a complementary in vitro study adding ALA to hepatocytes media that showed some of the effects on the TCA cycle were parallel to those observed in vivo. Our study confirms in plasma previous results obtained in urine showing that AIP patients present a moderate increase of the kynurenine/tryptophan ratio possibly associated with inflammation. In addition, it also reports changes in the mitochondrial TCA cycle that, despite requiring further research, could be associated with an energy misbalance due to sustained overproduction of heme-precursors in the liver.
    Keywords:  LC-MS/MS; acute intermittent porphyria; kynurenine; metabolomics; tricarboxylic acid cycle; tryptophan
    DOI:  https://doi.org/10.3390/ijms23063219
  36. Cancer Res. 2022 Mar 22. pii: canres.CAN-22-0431-E.2022. [Epub ahead of print]
    Bcl-xL enforces a slow-cycling state necessary for survival in the nutrient-deprived microenvironment of pancreatic cancer.
    Yogev Sela, Jinyang Li, Shivahamy Maheswaran, Robert J Norgard, Salina Yuan, Maimon E Hubbi, Miriam Doepner, Jimmy P Xu, Elaine S Ho, Clementina Mesaros, Colin Sheehan, Grace Croley, Alexander Muir, Ian A Blair, Ophir Shalem, Chi V Dang, Ben Z Stanger.
      Solid tumors possess heterogeneous metabolic microenvironments where oxygen and nutrient availability are plentiful ('fertile regions') or scarce ('arid regions'). While cancer cells residing in fertile regions proliferate rapidly, most cancer cells in vivo reside in arid regions and exhibit a slow-cycling state that renders them chemoresistant. Here, we developed an in vitro system enabling systematic comparison between these populations via transcriptome analysis, metabolomic profiling, and whole-genome CRISPR screening. Metabolic deprivation led to pronounced transcriptional and metabolic reprogramming, resulting in decreased anabolic activities and distinct vulnerabilities. Reductions in anabolic, energy-consuming activities, particularly cell proliferation, were not simply byproducts of the metabolic challenge but rather essential adaptations. Mechanistically, Bcl-xL played a central role in the adaptation to nutrient and oxygen deprivation. In this setting, Bcl-xL protected quiescent cells from the lethal effects of cell cycle entry in the absence of adequate nutrients. Moreover, inhibition of Bcl-xL combined with traditional chemotherapy had a synergistic anti-tumor effect that targeted cycling cells. Bcl-xL expression was strongly associated with poor patient survival despite being confined to the slow-cycling fraction of human pancreatic cancer cells. These findings provide a rationale for combining traditional cancer therapies that target rapidly cycling cells with those that target quiescent, chemoresistant cells associated with nutrient and oxygen deprivation.
    DOI:  https://doi.org/10.1158/0008-5472.CAN-22-0431
  37. J Biomed Sci. 2022 Mar 25. 29(1): 21
    Reprogramming of arachidonate metabolism confers temozolomide resistance to glioblastoma through enhancing mitochondrial activity in fatty acid oxidation.
    Yu-Ting Tsai, Wei-Lun Lo, Pin-Yuan Chen, Chiung-Yuan Ko, Jian-Ying Chuang, Tzu-Jen Kao, Wen-Bing Yang, Kwang-Yu Chang, Chia-Yang Hung, Ushio Kikkawa, Wen-Chang Chang, Tsung-I Hsu.
       BACKGROUND: Sp1 is involved in the recurrence of glioblastoma (GBM) due to the acquirement of resistance to temozolomide (TMZ). Particularly, the role of Sp1 in metabolic reprogramming for drug resistance remains unknown.
    METHODS: RNA-Seq and mass spectrometry were used to analyze gene expression and metabolites amounts in paired GBM specimens (primary vs. recurrent) and in paired GBM cells (sensitive vs. resistant). ω-3/6 fatty acid and arachidonic acid (AA) metabolism in GBM patients were analyzed by targeted metabolome. Mitochondrial functions were determined by Seahorse XF Mito Stress Test, RNA-Seq, metabolome and substrate utilization for producing ATP. Therapeutic options targeting prostaglandin (PG) E2 in TMZ-resistant GBM were validated in vitro and in vivo.
    RESULTS: Among the metabolic pathways, Sp1 increased the prostaglandin-endoperoxide synthase 2 expression and PGE2 production in TMZ-resistant GBM. Mitochondrial genes and metabolites were obviously increased by PGE2, and these characteristics were required for developing resistance in GBM cells. For inducing TMZ resistance, PGE2 activated mitochondrial functions, including fatty acid β-oxidation (FAO) and tricarboxylic acid (TCA) cycle progression, through PGE2 receptors, E-type prostanoid (EP)1 and EP3. Additionally, EP1 antagonist ONO-8713 inhibited the survival of TMZ-resistant GBM synergistically with TMZ.
    CONCLUSION: Sp1-regulated PGE2 production activates FAO and TCA cycle in mitochondria, through EP1 and EP3 receptors, resulting in TMZ resistance in GBM. These results will provide us a new strategy to attenuate drug resistance or to re-sensitize recurred GBM.
    Keywords:  Fatty acid β-oxidation; Mitochondria; PGE2; Sp1; TMZ-resistant GBM
    DOI:  https://doi.org/10.1186/s12929-022-00804-3
  38. World J Gastrointest Oncol. 2022 Feb 15. 14(2): 478-497
    Comprehensive molecular characterization and identification of prognostic signature in stomach adenocarcinoma on the basis of energy-metabolism-related genes.
    Jin-Jia Chang, Xiao-Yu Wang, Wei Zhang, Cong Tan, Wei-Qi Sheng, Mi-Die Xu.
       BACKGROUND: Stomach adenocarcinoma (STAD) is a leading cause of cancer deaths, but its molecular and prognostic characteristics has never been fully illustrated.
    AIM: To describe a molecular evaluation of primary STAD and develop new therapies and identify promising prognostic signatures.
    METHODS: We describe a comprehensive molecular evaluation of primary STAD based on comprehensive analysis of energy-metabolism-related gene (EMRG) expression profiles.
    RESULTS: On the basis of 86 EMRGs that were significantly associated to patients' progression-free survival (PFS), we propose a molecular classification dividing gastric cancer into two subtypes: Cluster 1, most of which are young patients and display more immune and stromal cell components in tumor microenvironment and lower tumor priority; and Cluster 2, which show early stages and better PFS. Moreover, we construct a 6-gene signature that can classify the prognostic risk of patients after a three-phase training test and validation process. Compared with patients with low-risk score, patients with high-risk score had shorter overall survival. Furthermore, calibration and DCA analysis plots indicate the excellent predictive performance of the 6-gene signature, and which present higher robustness and clinical usability compared with three previous reported prognostic gene signatures. According to gene set enrichment analysis, gene sets related to the high-risk group were participated in the ECM receptor interaction and hedgehog signaling pathway.
    CONCLUSION: Identification of the EMRG-based molecular subtypes and prognostic gene model provides a roadmap for patient stratification and trials of targeted therapies.
    Keywords:  Energy-metabolism-related genes; Gastric cancer; Molecular subtype; Prognosis factor; Roadmap
    DOI:  https://doi.org/10.4251/wjgo.v14.i2.478
  39. Antioxidants (Basel). 2022 Mar 16. pii: 560. [Epub ahead of print]11(3):
    A Metabolic Network Mediating the Cycling of Succinate, a Product of ROS Detoxification into α-Ketoglutarate, an Antioxidant.
    Félix Legendre, Alex MacLean, Sujeenthar Tharmalingam, Vasu D Appanna.
      Sulfur is an essential element for life. However, the soil microbe Pseudomonas (P.) fluorescens can survive in a low sulfur environment. When cultured in a sulfur-deficient medium, the bacterium reprograms its metabolic pathways to produce α-ketoglutarate (KG) and regenerate this keto-acid from succinate, a by-product of ROS detoxification. Succinate semialdehyde dehydrogenase (SSADH) and KG decarboxylase (KGDC) work in partnership to synthesize KG. This process is further aided by the increased activity of the enzymes glutamate decarboxylase (GDC) and γ-amino-butyrate transaminase (GABAT). The pool of succinate semialdehyde (SSA) generated is further channeled towards the formation of the antioxidant. Spectrophotometric analyses, HPLC experiments and electrophoretic studies with intact cells and cell-free extracts (CFE) pointed to the metabolites (succinate, SSA, GABA) and enzymes (SSADH, GDC, KGDC) contributing to this KG-forming metabolic machinery. Real-time polymerase chain reaction (RT-qPCR) revealed significant increase in transcripts of such enzymes as SSADH, GDC and KGDC. The findings of this study highlight a novel pathway involving keto-acids in ROS scavenging. The cycling of succinate into KG provides an efficient means of combatting an oxidative environment. Considering the central role of KG in biological processes, this metabolic network may be operative in other living systems.
    Keywords:  KG; glutamate decarboxylase; metabolic network; oxidative stress; succinate recycling; sulfur stress
    DOI:  https://doi.org/10.3390/antiox11030560
  40. Mol Cell. 2022 Mar 14. pii: S1097-2765(22)00166-6. [Epub ahead of print]
    Hexokinase 1 cellular localization regulates the metabolic fate of glucose.
    Adam De Jesus, Farnaz Keyhani-Nejad, Carolina M Pusec, Lauren Goodman, Justin A Geier, Joshua S Stoolman, Paulina J Stanczyk, Tivoli Nguyen, Kai Xu, Krishna V Suresh, Yihan Chen, Arianne E Rodriguez, Jason S Shapiro, Hsiang-Chun Chang, Chunlei Chen, Kriti P Shah, Issam Ben-Sahra, Brian T Layden, Navdeep S Chandel, Samuel E Weinberg, Hossein Ardehali.
      The product of hexokinase (HK) enzymes, glucose-6-phosphate, can be metabolized through glycolysis or directed to alternative metabolic routes, such as the pentose phosphate pathway (PPP) to generate anabolic intermediates. HK1 contains an N-terminal mitochondrial binding domain (MBD), but its physiologic significance remains unclear. To elucidate the effect of HK1 mitochondrial dissociation on cellular metabolism, we generated mice lacking the HK1 MBD (ΔE1HK1). These mice produced a hyper-inflammatory response when challenged with lipopolysaccharide. Additionally, there was decreased glucose flux below the level of GAPDH and increased upstream flux through the PPP. The glycolytic block below GAPDH is mediated by the binding of cytosolic HK1 with S100A8/A9, resulting in GAPDH nitrosylation through iNOS. Additionally, human and mouse macrophages from conditions of low-grade inflammation, such as aging and diabetes, displayed increased cytosolic HK1 and reduced GAPDH activity. Our data indicate that HK1 mitochondrial binding alters glucose metabolism through regulation of GAPDH.
    Keywords:  GAPDH; S-nitrosylation; hexokinase; inflammation; innate immunity; macrophage; metabolism; mitochondria; pentose phosphate pathway; subcellular localization
    DOI:  https://doi.org/10.1016/j.molcel.2022.02.028
  41. Front Cell Neurosci. 2022 ;16 826193
    Evidence That Substantia Nigra Pars Compacta Dopaminergic Neurons Are Selectively Vulnerable to Oxidative Stress Because They Are Highly Metabolically Active.
    Anjie Ni, Carl Ernst.
      There are 400-500 thousand dopaminergic cells within each side of the human substantia nigra pars compacta (SNpc) making them a minuscule portion of total brain mass. These tiny clusters of cells have an outsized impact on motor output and behavior as seen in disorders such as Parkinson's disease (PD). SNpc dopaminergic neurons are more vulnerable to oxidative stress compared to other brain cell types, but the reasons for this are not precisely known. Here we provide evidence to support the hypothesis that this selective vulnerability is because SNpc neurons sustain high metabolic rates compared to other neurons. A higher baseline requirement for ATP production may lead to a selective vulnerability to impairments in oxidative phosphorylation (OXPHOS) or genetic insults that impair Complex I of the electron transport chain. We suggest that the energy demands of the unique morphological and electrophysiological properties of SNpc neurons may be one reason these cells produce more ATP than other cells. We further provide evidence to support the hypothesis that transcription factors (TFs) required to drive induction, differentiation, and maintenance of midbrain dopaminergic neural progenitor cells which give rise to terminally differentiated SNpc neurons are uniquely involved in both developmental patterning and metabolism, a dual function unlike other TFs that program neurons in other brain regions. The use of these TFs during induction and differentiation may program ventral midbrain progenitor cells metabolically to higher ATP levels, allowing for the development of those specialized cell processes seen in terminally differentiated cells. This paper provides a cellular and developmental framework for understanding the selective vulnerability of SNpc dopaminergic cells to oxidative stress.
    Keywords:  FOXA; LMX1; NR4A2; dopamine; midbrain development
    DOI:  https://doi.org/10.3389/fncel.2022.826193
  42. Biomedicines. 2022 Mar 19. pii: 717. [Epub ahead of print]10(3):
    Combined HP 13C Pyruvate and 13C-Glucose Fluxomic as a Potential Marker of Response to Targeted Therapies in YUMM1.7 Melanoma Xenografts.
    Chantale Farah, Marie-Aline Neveu, Caner Yelek, Caroline Bouzin, Bernard Gallez, Jean-François Baurain, Lionel Mignion, Bénédicte F Jordan.
      A vast majority of BRAF V600E mutated melanoma patients will develop resistance to combined BRAF/MEK inhibition after initial clinical response. Resistance to targeted therapy is described to be accompanied by specific metabolic changes in melanoma. The aim of this work was to evaluate metabolic imaging using 13C-MRS (Magnetic Resonance Spectroscopy) as a marker of response to BRAF/MEK inhibition in a syngeneic melanoma model. Tumor growth was significantly delayed in mice bearing YUMM1.7 melanoma xenografts treated with the BRAF inhibitor vemurafenib, and/or with the MEK inhibitor trametinib, in comparison with the control group. 13C-MRS was performed in vivo after injection of hyperpolarized (HP) 13C-pyruvate, at baseline and 24 h after treatment, to evaluate dynamic changes in pyruvate-lactate exchange. Furthermore, ex vivo 13C-MRS steady state metabolic tracing experiments were performed after U-13C-glucose or 5-13C-glutamine injection, 24 h after treatment. The HP 13C-lactate-to-pyruvate ratio was not modified in response to BRAF/MEK inhibition, whereas the production of 13C-lactate from 13C-glucose was significantly reduced 24 h after treatment with vemurafenib, trametinib, or with the combined inhibitors. Conversely, 13C-glutamine metabolism was not modified in response to BRAF/MEK inhibition. In conclusion, we identified 13C-glucose fluxomic as a potential marker of response to BRAF/MEK inhibition in YUMM1.7 melanoma xenografts.
    Keywords:  13C-MRS; BRAF and MEK inhibition; markers of response; melanoma; targeted therapy; tumor metabolism
    DOI:  https://doi.org/10.3390/biomedicines10030717
  43. Anal Chem. 2022 Mar 21.
    Combination of Electrochemistry and Mass Spectrometry to Study Nitric Oxide Metabolism and Its Modulation by Compound K in Breast Cancer Cells.
    Mingyue Zhao, Xin Liu, Yuzhu Hou, Tongtong Yang, Jiaquan Xu, Rui Su.
      The levels of l-arginine and asymmetric dimethylarginine (ADMA) and the amount of the nitric oxide (NO) production have recently been linked to breast cancer and pharmaceutical effect evaluation. Herein, a method combining electrochemistry and high-resolution mass spectrometry (HRMS) was established and used to study NO metabolism and its modulation by ginsenoside compound K (CK) in breast cancer cells. Platinum nanoparticles-decorated fluorine tin oxide was employed as an electrochemical sensor for in situ detection of NO release, while HRMS was used for the analysis of the NO-related metabolites. Through the combination of the electrochemical and HRMS results, decreases in arginine and NO and increases in ADMA and ornithine were observed after modulation by CK, and two highly correlated metabolic pathways including arginine and proline metabolism and vascular smooth muscle contraction were found. This method offers a new strategy for fast evaluation of pharmaceutical efficacy based on NO metabolism.
    DOI:  https://doi.org/10.1021/acs.analchem.1c05492
  44. Phytomedicine. 2022 Mar 15. pii: S0944-7113(22)00126-X. [Epub ahead of print]100 154048
    Lactate metabolism in rheumatoid arthritis: Pathogenic mechanisms and therapeutic intervention with natural compounds.
    Ouyang Yi, Ye Lin, Mingyue Hu, Shengtao Hu, Zhaoli Su, Jin Liao, Bin Liu, Liang Liu, Xiong Cai.
       BACKGROUND: Rheumatoid arthritis (RA) is a common chronic and systemic autoimmune disease characterized by persistent inflammation and hyperplasia of the synovial membrane, the degradation of cartilage, and the erosion of bones in diarthrodial joints. The inflamed joints of patients with RA have been recognized to be a site of hypoxic microenvironment which results in an imbalance of lactate metabolism and the accumulation of lactate. Lactate is no longer considered solely a metabolic waste product of glycolysis, but also a combustion aid in the progression of RA from the early stages of inflammation to the late stages of bone destruction.
    PURPOSE: To review the pathogenic mechanisms of lactate metabolism in RA and investigate the potential of natural compounds for treating RA linked to the regulation of imbalance in lactate metabolism.
    METHODS: Research advances in our understanding of lactate metabolism in the pathogenesis of RA and novel pharmacological approaches of natural compounds by targeting lactate metabolic signaling were comprehensively reviewed and deeply discussed.
    RESULTS: Lactate produced by RA synovial fibroblasts (RASFs) acts on targeted cells such as T cells, macrophages, dendritic cells and osteoclasts, and affects their differentiation, activation and function to accelerate the development of RA. Many natural compounds show therapeutic potential for RA by regulating glycolytic rate-limiting enzymes to limit lactate production, and affecting monocarboxylate transporter and acetyl-CoA carboxylase to inhibit lactate transport and conversion.
    CONCLUSION: Regulation of imbalance in lactate metabolism offers novel therapeutic approaches for RA, and natural compounds capable of targeting lactate metabolic signaling constitute potential candidates for development of drugs RA.
    Keywords:  Hypoxic microenvironment; Lactate metabolism; Natural compounds; Rheumatoid arthritis; Synovial fibroblasts
    DOI:  https://doi.org/10.1016/j.phymed.2022.154048
  45. Cells. 2022 Mar 08. pii: 930. [Epub ahead of print]11(6):
    Oxidative Stress Differentially Influences the Survival and Metabolism of Cells in the Melanoma Microenvironment.
    Emily R Trzeciak, Niklas Zimmer, Isabelle Gehringer, Lara Stein, Barbara Graefen, Jonathan Schupp, Achim Stephan, Stephan Rietz, Michael Prantner, Andrea Tuettenberg.
      The cellular composition of the tumor microenvironment, including tumor, immune, stromal, and endothelial cells, significantly influences responses to cancer therapies. In this study, we analyzed the impact of oxidative stress, induced by cold atmospheric plasma (CAP), on tumor cells, T cells, and macrophages, which comprise part of the melanoma microenvironment. To accomplish this, cells were grown in different in vitro cell culture models and were treated with varying amounts of CAP. Subsequent alterations in viability, proliferation, and phenotype were analyzed via flow cytometry and metabolic alterations by Seahorse Cell Mito Stress Tests. It was found that cells generally exhibited reduced viability and proliferation, stemming from CAP induced G2/M cell cycle arrest and subsequent apoptosis, as well as increased mitochondrial stress following CAP treatment. Overall, sensitivity to CAP treatment was found to be cell type dependent with T cells being the most affected. Interestingly, CAP influenced the polarization of M0 macrophages to a "M0/M2-like" phenotype, and M1 macrophages were found to display a heightened sensitivity to CAP induced mitochondrial stress. CAP also inhibited the growth and killed melanoma cells in 2D and 3D in vitro cell culture models in a dose-dependent manner. Improving our understanding of oxidative stress, mechanisms to manipulate it, and its implications for the tumor microenvironment may help in the discovery of new therapeutic targets.
    Keywords:  T cell; cold atmospheric plasma; macrophage; malignant melanoma; metabolic alterations; plasma jet; tumor microenvironment; tumor spheroids; tumor therapy
    DOI:  https://doi.org/10.3390/cells11060930
  46. EMBO J. 2022 Mar 21. e110466
    Ketogenic HMG-CoA lyase and its product β-hydroxybutyrate promote pancreatic cancer progression.
    Victoire Gouirand, Tristan Gicquel, Evan C Lien, Emilie Jaune-Pons, Quentin Da Costa, Pascal Finetti, Elodie Metay, Camille Duluc, Jared R Mayers, Stephane Audebert, Luc Camoin, Laurence Borge, Marion Rubis, Julie Leca, Jeremy Nigri, François Bertucci, Nelson Dusetti, Juan Lucio Iovanna, Richard Tomasini, Ghislain Bidaut, Fabienne Guillaumond, Matthew G Vander Heiden, Sophie Vasseur.
      Pancreatic ductal adenocarcinoma (PDA) tumor cells are deprived of oxygen and nutrients and therefore must adapt their metabolism to ensure proliferation. In some physiological states, cells rely on ketone bodies to satisfy their metabolic needs, especially during nutrient stress. Here, we show that PDA cells can activate ketone body metabolism and that β-hydroxybutyrate (βOHB) is an alternative cell-intrinsic or systemic fuel that can promote PDA growth and progression. PDA cells activate enzymes required for ketogenesis, utilizing various nutrients as carbon sources for ketone body formation. By assessing metabolic gene expression from spontaneously arising PDA tumors in mice, we find HMG-CoA lyase (HMGCL), involved in ketogenesis, to be among the most deregulated metabolic enzymes in PDA compared to normal pancreas. In vitro depletion of HMGCL impedes migration, tumor cell invasiveness, and anchorage-independent tumor sphere compaction. Moreover, disrupting HMGCL drastically decreases PDA tumor growth in vivo, while βOHB stimulates metastatic dissemination to the liver. These findings suggest that βOHB increases PDA aggressiveness and identify HMGCL and ketogenesis as metabolic targets for limiting PDA progression.
    Keywords:  HMGCL; ketone bodies; metastasis; pancreatic cancer; β-hydroxybutyrate
    DOI:  https://doi.org/10.15252/embj.2021110466
  47. Cells. 2022 Mar 18. pii: 1041. [Epub ahead of print]11(6):
    Tumor Cell Glycolysis-At the Crossroad of Epithelial-Mesenchymal Transition and Autophagy.
    Fabrizio Marcucci, Cristiano Rumio.
      Upregulation of glycolysis, induction of epithelial-mesenchymal transition (EMT) and macroautophagy (hereafter autophagy), are phenotypic changes that occur in tumor cells, in response to similar stimuli, either tumor cell-autonomous or from the tumor microenvironment. Available evidence, herein reviewed, suggests that glycolysis can play a causative role in the induction of EMT and autophagy in tumor cells. Thus, glycolysis has been shown to induce EMT and either induce or inhibit autophagy. Glycolysis-induced autophagy occurs both in the presence (glucose starvation) or absence (glucose sufficiency) of metabolic stress. In order to explain these, in part, contradictory experimental observations, we propose that in the presence of stimuli, tumor cells respond by upregulating glycolysis, which will then induce EMT and inhibit autophagy. In the presence of stimuli and glucose starvation, upregulated glycolysis leads to adenosine monophosphate-activated protein kinase (AMPK) activation and autophagy induction. In the presence of stimuli and glucose sufficiency, upregulated glycolytic enzymes (e.g., aldolase or glyceraldehyde 3-phosphate dehydrogenase) or decreased levels of glycolytic metabolites (e.g., dihydroxyacetone phosphate) may mimic a situation of metabolic stress (herein referred to as "pseudostarvation"), leading, directly or indirectly, to AMPK activation and autophagy induction. We also discuss possible mechanisms, whereby glycolysis can induce a mixed mesenchymal/autophagic phenotype in tumor cells. Subsequently, we address unresolved problems in this field and possible therapeutic consequences.
    Keywords:  AMPK; EMT; autophagy; glycolysis; mTOR; starvation
    DOI:  https://doi.org/10.3390/cells11061041
  48. Cell Rep. 2022 Mar 22. pii: S2211-1247(22)00306-0. [Epub ahead of print]38(12): 110562
    Thyroid hormone regulates glutamine metabolism and anaplerotic fluxes by inducing mitochondrial glutamate aminotransferase GPT2.
    Annunziata Gaetana Cicatiello, Serena Sagliocchi, Annarita Nappi, Emery Di Cicco, Caterina Miro, Melania Murolo, Mariano Stornaiuolo, Monica Dentice.
      
    DOI:  https://doi.org/10.1016/j.celrep.2022.110562
  49. J Clin Invest. 2022 Mar 22. pii: e153436. [Epub ahead of print]
    PHGDH is required for germinal center formation and is a therapeutic target in MYC-driven lymphoma.
    Annalisa D'Avola, Nathalie Legrave, Mylène Tajan, Probir Chakravarty, Ryan L Shearer, Hamish W King, Katarina Kluckova, Eric C Cheung, Andrew J Clear, Arief S Gunawan, Lingling Zhang, Louisa K James, James I MacRae, John G Gribben, Dinis P Calado, Karen H Vousden, John C Riches.
      The synthesis of serine from glucose is a key metabolic pathway supporting cellular proliferation in healthy and malignant cells. Despite this, the role that this aspect of metabolism plays in germinal center biology and pathology is not known. Here, we performed a comprehensive characterization of the role of the serine synthesis pathway in germinal center B cells and lymphomas derived from these cells. We demonstrated that upregulation of a functional serine synthesis pathway is a metabolic hallmark of B-cell activation and the germinal center reaction. Inhibition of phosphoglycerate dehydrogenase (PHGDH), the first and rate limiting enzyme in this pathway, led to defective germinal formation and impaired high-affinity antibody production. In addition, overexpression of enzymes involved in serine synthesis was a characteristic of germinal center B-cell derived lymphomas, with high levels of expression being predictive of reduced overall survival in diffuse large B cell lymphoma. Inhibition of PHGDH induced apoptosis in lymphoma cells reducing disease progression. These findings establish PHGDH as a critical player in humoral immunity and a clinically relevant target in lymphoma.
    Keywords:  Amino acid metabolism; Immunoglobulins; Immunology; Lymphomas; Metabolism
    DOI:  https://doi.org/10.1172/JCI153436
  50. Cancers (Basel). 2022 Mar 16. pii: 1531. [Epub ahead of print]14(6):
    NRF2 and Key Transcriptional Targets in Melanoma Redox Manipulation.
    Evan L Carpenter, Alyssa L Becker, Arup K Indra.
      Melanocytes are dendritic, pigment-producing cells located in the skin and are responsible for its protection against the deleterious effects of solar ultraviolet radiation (UVR), which include DNA damage and elevated reactive oxygen species (ROS). They do so by synthesizing photoprotective melanin pigments and distributing them to adjacent skin cells (e.g., keratinocytes). However, melanocytes encounter a large burden of oxidative stress during this process, due to both exogenous and endogenous sources. Therefore, melanocytes employ numerous antioxidant defenses to protect themselves; these are largely regulated by the master stress response transcription factor, nuclear factor erythroid 2-related factor 2 (NRF2). Key effector transcriptional targets of NRF2 include the components of the glutathione and thioredoxin antioxidant systems. Despite these defenses, melanocyte DNA often is subject to mutations that result in the dysregulation of the proliferative mitogen-activated protein kinase (MAPK) pathway and the cell cycle. Following tumor initiation, endogenous antioxidant systems are co-opted, a consequence of elevated oxidative stress caused by metabolic reprogramming, to establish an altered redox homeostasis. This altered redox homeostasis contributes to tumor progression and metastasis, while also complicating the application of exogenous antioxidant treatments. Further understanding of melanocyte redox homeostasis, in the presence or absence of disease, would contribute to the development of novel therapies to aid in the prevention and treatment of melanomas and other skin diseases.
    Keywords:  HO-1; HSP70; NQO1; NRF2; SOD; antioxidant; glutathione; melanoma; peroxiredoxin; thioredoxin
    DOI:  https://doi.org/10.3390/cancers14061531
  51. J Cancer Res Clin Oncol. 2022 Mar 21.
    Analysis of N6-methyladenosine-related lncRNAs in the tumor immune microenvironment and their prognostic role in pancreatic cancer.
    Yong Liu, Tao Wang, Ziqi Fang, Junjie Kong, Jun Liu.
       BACKGROUND: Pancreatic cancer (PC) is a rare solid malignancy with a poor prognosis. N6-methyladenosine (m6A) and long noncoding RNAs (lncRNAs) play essential roles in tumorigenesis and progression. However, little is known about the role of m6A-related lncRNAs in PC.
    METHODS: m6A-related lncRNAs were extracted by Pearson analysis, and then prognosis-related lncRNAs were filtered from the m6A-related lncRNAs by univariate Cox regression analysis. Based on the expression patterns of the prognosis-related lncRNAs, samples were classified into distinct clusters. Least absolute shrinkage and selection operator (LASSO) Cox regression was used to construct a m6A-lncRNA-related prognostic signature for PC patients. Receiver operating characteristic (ROC) curves and the corresponding area under the curve (AUC) values were used to evaluate the prognostic ability of the model.
    RESULTS: A total of 178 tumor and 4 normal samples were extracted from The Cancer Genome Atlas (TCGA) database in our study. Based on the expression of 12 filtered prognosis-related lncRNAs, two distinct clusters were eventually identified; these clusters were characterized by differences in the tumor immune microenvironment (TIME) and prognosis. A risk model comprising ten m6A-related lncRNAs was identified as an independent predictor of prognosis. ROC analysis revealed that this model had an acceptable prognostic value for PC patients. The prognostic signature was related to the TIME and the expression of critical immune checkpoint molecules.
    CONCLUSION: This study comprehensively assessed the expression pattern and prognostic value of m6A-related lncRNAs in PC. The different clusters correlated with distinct TIMEs and prognoses. The study also constructed a ten-gene signature prognostic model based on m6A-related lncRNAs, which showed good accuracy in predicting overall survival.
    Keywords:  N6-methyladenosine; Pancreatic cancer; Prognostic signature; Tumor immune microenvironment; lncRNAs
    DOI:  https://doi.org/10.1007/s00432-022-03985-4
  52. Cell Stem Cell. 2022 Mar 22. pii: S1934-5909(22)00097-2. [Epub ahead of print]
    PPARdelta activation induces metabolic and contractile maturation of human pluripotent stem-cell-derived cardiomyocytes.
    Nadeera M Wickramasinghe, David Sachs, Bhavana Shewale, David M Gonzalez, Priyanka Dhanan-Krishnan, Denis Torre, Elizabeth LaMarca, Serena Raimo, Rafael Dariolli, Madhavika N Serasinghe, Joshua Mayourian, Robert Sebra, Kristin Beaumont, Srinivas Iyengar, Deborah L French, Arne Hansen, Thomas Eschenhagen, Jerry E Chipuk, Eric A Sobie, Adam Jacobs, Schahram Akbarian, Harry Ischiropoulos, Avi Ma'ayan, Sander M Houten, Kevin Costa, Nicole C Dubois.
      Pluripotent stem-cell-derived cardiomyocytes (PSC-CMs) provide an unprecedented opportunity to study human heart development and disease, but they are functionally and structurally immature. Here, we induce efficient human PSC-CM (hPSC-CM) maturation through metabolic-pathway modulations. Specifically, we find that peroxisome-proliferator-associated receptor (PPAR) signaling regulates glycolysis and fatty acid oxidation (FAO) in an isoform-specific manner. While PPARalpha (PPARa) is the most active isoform in hPSC-CMs, PPARdelta (PPARd) activation efficiently upregulates the gene regulatory networks underlying FAO, increases mitochondrial and peroxisome content, enhances mitochondrial cristae formation, and augments FAO flux. PPARd activation further increases binucleation, enhances myofibril organization, and improves contractility. Transient lactate exposure, which is frequently used for hPSC-CM purification, induces an independent cardiac maturation program but, when combined with PPARd activation, still enhances oxidative metabolism. In summary, we investigate multiple metabolic modifications in hPSC-CMs and identify a role for PPARd signaling in inducing the metabolic switch from glycolysis to FAO in hPSC-CMs.
    Keywords:  PPAR signaling; cardiac maturation; fatty acid oxidation; metabolism; stem cells
    DOI:  https://doi.org/10.1016/j.stem.2022.02.011
  53. Biomolecules. 2022 Feb 24. pii: 361. [Epub ahead of print]12(3):
    Sulfide Oxidation Evidences the Immediate Cellular Response to a Decrease in the Mitochondrial ATP/O2 Ratio.
    Frédéric Bouillaud.
      The present article will not attempt to deal with sulfide per se as a signaling molecule but will aim to examine the consequences of sulfide oxidation by mitochondrial sulfide quinone reductase in mammalian cells. This oxidation appears first as a priority to avoid self-poisoning by endogenous sulfide and second to occur with the lowest ATP/O2 ratio when compared to other mitochondrial substrates. This is explained by the injection of electrons in the respiratory chain after complex I (as for succinate) and by a sulfur oxidation step implying a dioxygenase that consumes oxygen but does not contribute to mitochondrial bioenergetics. Both contribute to increase cellular oxygen consumption if sulfide is provided below its toxic level (low µM). Accordingly, if oxygen supply or respiratory chain activity becomes a limiting factor, small variations in sulfide release impact the cellular ATP/ADP ratio, a major metabolic sensor.
    Keywords:  ATP/ADP ratio; bioenergetics; dioxygenase; mitochondria; oxygen; oxygen-sensing; redox state; succinate
    DOI:  https://doi.org/10.3390/biom12030361
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