bims-celmim 2024-07-14 papers

bims-celmim

Biomed News

on Cellular and mitochondrial metabolism

Issue of 2024–07–14
27 papers selected by
Marc Segarra Mondejar

The Role of Mitochondrial Sirtuins (SIRT3, SIRT4 and SIRT5) in Renal Cell Metabolism: Implication for Kidney Diseases.
Lactate promotes fatty acid oxidation by the TCA cycle and mitochondrial respiration in muscles of obese mice.
Differential regulation of mitochondrial uncoupling protein 2 in cancer cells.
Hexokinase 1 forms rings that regulate mitochondrial fission during energy stress.
Syntheses and Applications of Coumarin-Derived Fluorescent Probes for Real-Time Monitoring of NAD(P)H Dynamics in Living Cells across Diverse Chemical Environments.
The iAAA-mitochondrial protease YME1L1 regulates the degradation of the short-lived mitochondrial transporter SLC25A38.
Homeostatic regulation of NAD(H) and NADP(H) in cells.
Mitophagy and clear cell renal cell carcinoma: insights from single-cell and spatial transcriptomics analysis.
Protocol for performing metabolic pathway-based subtyping of breast tumors.
Slc25a3-dependent copper transport controls flickering-induced Opa1 processing for mitochondrial safeguard.
Glucose-6-phosphate dehydrogenase maintains redox homeostasis and biosynthesis in LKB1-deficient KRAS-driven lung cancer.
Restoring hippocampal glucose metabolism rescues cognition across Alzheimer's disease pathologies.
Compartmentalized mitochondrial ferroptosis converges with optineurin-mediated mitophagy to impact airway epithelial cell phenotypes and asthma outcomes.
Genetically Encoded and Modular SubCellular Organelle Probes (GEM-SCOPe) reveal lysosomal and mitochondrial dysfunction driven by PRKN knockout.
Metabolic profiling of single cells by exploiting NADH and FAD fluorescence via flow cytometry.
Origin and Roles of Alanine and Glutamine in Gluconeogenesis in the Liver, Kidneys, and Small Intestine under Physiological and Pathological Conditions.
Interorganelle phospholipid communication, a house not so divided.
Let's talk about flux: the rising potential of autophagy rate measurements in disease.
Thrifty tissues prefer recycled purines over new-cleotides.
Phosphoglycerate mutase regulates Treg differentiation through control of serine synthesis and one-carbon metabolism.
Purinosomes and Purine Metabolism in Mammalian Neural Development: A Review.
The Protective Effect of Uridine in a Rotenone-Induced Model of Parkinson's Disease: The Role of the Mitochondrial ATP-Dependent Potassium Channel.
Egg multivesicular bodies elicit an LC3-associated phagocytosis-like pathway to degrade paternal mitochondria after fertilization.
Metabolic reprograming mediated by tumor cell-intrinsic type I IFN signaling is required for CD47-SIRPα blockade efficacy.
Coordinated Regulation of Renal Glucose Reabsorption and Gluconeogenesis by mTORC2 and Potassium.
Integrated translation and metabolism in a partially self-synthesizing biochemical network.
Norovirus NS1/2 protein increases glutaminolysis for efficient viral replication.

Int J Mol Sci. 2024 Jun 25. pii: 6936. [Epub ahead of print]25(13):

The Role of Mitochondrial Sirtuins (SIRT3, SIRT4 and SIRT5) in Renal Cell Metabolism: Implication for Kidney Diseases.

Florian Juszczak, Thierry Arnould, Anne-Emilie Declèves.

  Kidney diseases, including chronic kidney disease (CKD), diabetic nephropathy, and acute kidney injury (AKI), represent a significant global health burden. The kidneys are metabolically very active organs demanding a large amount of ATP. They are composed of highly specialized cell types in the glomerulus and subsequent tubular compartments which fine-tune metabolism to meet their numerous and diverse functions. Defective renal cell metabolism, including altered fatty acid oxidation or glycolysis, has been linked to both AKI and CKD. Mitochondria play a vital role in renal metabolism, and emerging research has identified mitochondrial sirtuins (SIRT3, SIRT4 and SIRT5) as key regulators of renal cell metabolic adaptation, especially SIRT3. Sirtuins belong to an evolutionarily conserved family of mainly NAD+-dependent deacetylases, deacylases, and ADP-ribosyl transferases. Their dependence on NAD+, used as a co-substrate, directly links their enzymatic activity to the metabolic status of the cell. In the kidney, SIRT3 has been described to play crucial roles in the regulation of mitochondrial function, and the antioxidative and antifibrotic response. SIRT3 has been found to be constantly downregulated in renal diseases. Genetic or pharmacologic upregulation of SIRT3 has also been associated with beneficial renal outcomes. Importantly, experimental pieces of evidence suggest that SIRT3 may act as an important energy sensor in renal cells by regulating the activity of key enzymes involved in metabolic adaptation. Activation of SIRT3 may thus represent an interesting strategy to ameliorate renal cell energetics. In this review, we discuss the roles of SIRT3 in lipid and glucose metabolism and in mediating a metabolic switch in a physiological and pathological context. Moreover, we highlight the emerging significance of other mitochondrial sirtuins, SIRT4 and SIRT5, in renal metabolism. Understanding the role of mitochondrial sirtuins in kidney diseases may also open new avenues for innovative and efficient therapeutic interventions and ultimately improve the management of renal injuries.

Keywords:  SIRT3; SIRT4; SIRT5; glucose metabolism; kidney disease; lipid metabolism; lipotoxicity; metabolic switch; mitochondrial homeostasis; sirtuins

DOI:  https://doi.org/10.3390/ijms25136936
Am J Physiol Cell Physiol. 2024 Jul 09.

Lactate promotes fatty acid oxidation by the TCA cycle and mitochondrial respiration in muscles of obese mice.

Soi-Yi Park, Su-Ryun Jung, Jong-Yeon Kim, Yong-Woon Kim, Hoon-Ki Sung, So-Young Park, Kyung-Oh Doh, Jin-Ho Koh.

  Lower oxidative capacity in skeletal muscles (SKMs) is a prevailing cause of metabolic diseases. Exercise not only enhances the fatty acid oxidation (FAO) capacity of SKMs but also increases lactate levels. Given that lactate may contribute to tricarboxylic acid cycle (TCA) flux and impact monocarboxylate transporter 1 in the SKMs, we hypothesize that lactate can influence glucose and fatty acid (FA) metabolism. To test this hypothesis, we investigated the mechanism underlying lactate-driven FAO regulation in the SKM of mice with diet-induced obesity (DIO). Lactate was administered to DIO mice immediately after exercise over three weeks. We found that increased lactate levels enhanced energy expenditure mediated by fat metabolism during exercise recovery and decreased triglyceride levels in DIO mice SKMs. To determine the lactate-specific effects without exercise, we administered lactate to mice on a high-fat diet (HFD) for eight weeks. Similar to our exercise conditions, lactate increased FAO, TCA cycle activity, and mitochondrial respiration in the SKMs of HFD-fed mice. Additionally, under sufficient FA conditions, lactate increased uncoupling protein-3 abundance via the NADH/NAD+ shuttle. Conversely ATP synthase abundance decreased in the SKMs of HFD mice. Taken together, our results suggest that lactate amplifies the adaptive increase in FAO capacity mediated by the TCA cycle and mitochondrial respiration in SKMs under sufficient FA abundance.

Keywords:  Exercise; Fatty acid oxidation; Lactate; Mitochondrial respiration; TCA cycle

DOI:  https://doi.org/10.1152/ajpcell.00060.2024
Biochim Biophys Acta Bioenerg. 2024 Jul 08. pii: S0005-2728(24)00456-0. [Epub ahead of print] 149486

Differential regulation of mitochondrial uncoupling protein 2 in cancer cells.

Taraneh Beikbaghban, Ludovica Proietti, Jessica Ebner, Roko Sango, Thomas Rattei, Thomas Weichhart, Florian Grebien, Felix Sternberg, Elena E Pohl.

  The persistent growth of cancer cells is underscored by complex metabolic reprogramming, with mitochondria playing a key role in the transition to aerobic glycolysis and representing new therapeutic targets. Mitochondrial uncoupling protein 2 (UCP2) has attracted interest because of its abundance in rapidly proliferating cells, including cancer cells, and its involvement in cellular metabolism. However, the specific contributions of UCP2 to cancer biology remain poorly defined. Our investigation of UCP2 expression in various human and mouse cancer cell lines aimed to elucidate its links to metabolic states, proliferation, and adaptation to environmental stresses such as hypoxia and nutrient deprivation. We observed significant variability in UCP2 expression across cancer types, with no direct correlation to their metabolic activity or proliferation rates. UCP2 abundance was also differentially affected by nutrient availability in different cancer cells, but UCP2 was generally downregulated under hypoxia. These findings challenge the notion that UCP2 is a marker of malignant potential and suggest its more complex involvement in the metabolic landscape of cancer.

Keywords:  Citric acid cycle; Extracellular acidification rate; Metabolite transport; Oxygen consumption rate; Pyruvate kinase; Uncouplers; Warburg effect

DOI:  https://doi.org/10.1016/j.bbabio.2024.149486
Mol Cell. 2024 Jun 28. pii: S1097-2765(24)00512-4. [Epub ahead of print]

Hexokinase 1 forms rings that regulate mitochondrial fission during energy stress.

Johannes Pilic, Benjamin Gottschalk, Benjamin Bourgeois, Hansjörg Habisch, Zhanat Koshenov, Furkan E Oflaz, Yusuf C Erdogan, Seyed M Miri, Esra N Yiğit, Mehmet Ş Aydın, Gürkan Öztürk, Emrah Eroglu, Varda Shoshan-Barmatz, Tobias Madl, Wolfgang F Graier, Roland Malli.

  Metabolic enzymes can adapt during energy stress, but the consequences of these adaptations remain understudied. Here, we discovered that hexokinase 1 (HK1), a key glycolytic enzyme, forms rings around mitochondria during energy stress. These HK1-rings constrict mitochondria at contact sites with the endoplasmic reticulum (ER) and mitochondrial dynamics protein (MiD51). HK1-rings prevent mitochondrial fission by displacing the dynamin-related protein 1 (Drp1) from mitochondrial fission factor (Mff) and mitochondrial fission 1 protein (Fis1). The disassembly of HK1-rings during energy restoration correlated with mitochondrial fission. Mechanistically, we identified that the lack of ATP and glucose-6-phosphate (G6P) promotes the formation of HK1-rings. Mutations that affect the formation of HK1-rings showed that HK1-rings rewire cellular metabolism toward increased TCA cycle activity. Our findings highlight that HK1 is an energy stress sensor that regulates the shape, connectivity, and metabolic activity of mitochondria. Thus, the formation of HK1-rings may affect mitochondrial function in energy-stress-related pathologies.

Keywords:  ER-mitochondria contact sites; energy stress; glucose starvation; glycolysis; hexokinase; live-cell imaging; mitochondrial constriction; mitochondrial fission; non-catalytic functions; protein cluster

DOI:  https://doi.org/10.1016/j.molcel.2024.06.009
ACS Appl Bio Mater. 2024 Jul 12.

Syntheses and Applications of Coumarin-Derived Fluorescent Probes for Real-Time Monitoring of NAD(P)H Dynamics in Living Cells across Diverse Chemical Environments.

Adenike Mary Olowolagba, Micah Olamide Idowu, Dilka Liyana Arachchige, Omowunmi Rebecca Aworinde, Sushil K Dwivedi, Olivya Rose Graham, Thomas Werner, Rudy L Luck, Haiying Liu.

  Fluorescent probes play a crucial role in elucidating cellular processes, with NAD(P)H sensing being pivotal in understanding cellular metabolism and redox biology. Here, the development and characterization of three fluorescent probes, A, B, and C, based on the coumarin platform for monitoring of NAD(P)H levels in living cells are described. Probes A and B incorporate a coumarin-cyanine hybrid structure with vinyl and thiophene connection bridges to 3-quinolinium acceptors, respectively, while probe C introduces a dicyano moiety for replacement of the lactone carbonyl group of probe A which increases the reaction rate of the probe with NAD(P)H. Initially, all probes exhibit subdued fluorescence due to intramolecular charge transfer (ICT) quenching. However, upon hydride transfer by NAD(P)H, fluorescence activation is triggered through enhanced ICT. Theoretical calculations confirm that the electronic absorption changes upon the addition of hydride to originate from the quinoline moiety instead of the coumarin section and end up in the middle section, illustrating how the addition of hydride affects the nature of this absorption. Control and dose-response experiments provide conclusive evidence of probe C's specificity and reliability in identifying intracellular NAD(P)H levels within HeLa cells. Furthermore, colocalization studies indicate probe C's selective targeting of mitochondria. Investigation into metabolic substrates reveals the influence of glucose, maltose, pyruvate, lactate, acesulfame potassium, and aspartame on NAD(P)H levels, shedding light on cellular responses to nutrient availability and artificial sweeteners. Additionally, we explore the consequence of oxaliplatin on cellular NAD(P)H levels, revealing complex interplays between DNA damage repair, metabolic reprogramming, and enzyme activities. In vivo studies utilizing starved fruit fly larvae underscore probe C's efficacy in monitoring NAD(P)H dynamics in response to external compounds. These findings highlight probe C's utility as a versatile tool for investigating NAD(P)H signaling pathways in biomedical research contexts, offering insights into cellular metabolism, stress responses, and disease mechanisms.

Keywords:  NAD(P)H; artificial sugars; cellular imaging; coumarin; cyanine dyes; fluorescent probes

DOI:  https://doi.org/10.1021/acsabm.4c00595
bioRxiv. 2024 Jun 24. pii: 2024.05.12.593764. [Epub ahead of print]

The iAAA-mitochondrial protease YME1L1 regulates the degradation of the short-lived mitochondrial transporter SLC25A38.

Sijie Tan, Alisa Susan Dengler, Rami Zahi Darawsheh, Nora Kory.

Mitochondrial transporters facilitate the exchange of diverse metabolic intermediates across the inner mitochondrial membrane, ensuring an adequate supply of substrates and cofactors to support redox and biosynthetic reactions within the mitochondrial matrix. However, the regulatory mechanisms governing the abundance of these transporters, crucial for maintaining metabolic compartmentalization and mitochondrial functions, remain poorly defined. Through analysis of protein half-life data and mRNA-protein correlations, we identified SLC25A38, a mitochondrial glycine transporter, as a short- lived protein with a half-life of 4 hours under steady-state conditions. Pharmacological inhibition and genetic depletion of various cellular proteolytic systems revealed that SLC25A38 is rapidly degraded by the iAAA-mitochondrial protease YME1L1. Depolarization of the mitochondrial membrane potential induced by the mitochondrial uncoupler carbonyl cyanide m-chlorophenylhydrozone prevented the degradation of SLC25A38. This dual regulation of SLC25A38 abundance by YME1L1 and mitochondrial membrane potential suggests a link between SLC25A38 turnover, the integrity of the inner mitochondrial membrane, and electron transport chain function. These findings open avenues for investigating whether mitochondrial glycine import coordinates with mitochondrial bioenergetics.

DOI: https://doi.org/10.1101/2024.05.12.593764
Genes Dis. 2024 Sep;11(5): 101146

Homeostatic regulation of NAD(H) and NADP(H) in cells.

Luojun Chen, Xiaoke Xing, Pingfeng Zhang, Lulu Chen, Huadong Pei.

  Nicotinamide adenine dinucleotide (NAD+)/reduced NAD+ (NADH) and nicotinamide adenine dinucleotide phosphate (NADP+)/reduced NADP+ (NADPH) are essential metabolites involved in multiple metabolic pathways and cellular processes. NAD+ and NADH redox couple plays a vital role in catabolic redox reactions, while NADPH is crucial for cellular anabolism and antioxidant responses. Maintaining NAD(H) and NADP(H) homeostasis is crucial for normal physiological activity and is tightly regulated through various mechanisms, such as biosynthesis, consumption, recycling, and conversion between NAD(H) and NADP(H). The conversions between NAD(H) and NADP(H) are controlled by NAD kinases (NADKs) and NADP(H) phosphatases [specifically, metazoan SpoT homolog-1 (MESH1) and nocturnin (NOCT)]. NADKs facilitate the synthesis of NADP+ from NAD+, while MESH1 and NOCT convert NADP(H) into NAD(H). In this review, we summarize the physiological roles of NAD(H) and NADP(H) and discuss the regulatory mechanisms governing NAD(H) and NADP(H) homeostasis in three key aspects: the transcriptional and posttranslational regulation of NADKs, the role of MESH1 and NOCT in maintaining NAD(H) and NADP(H) homeostasis, and the influence of the circadian clock on NAD(H) and NADP(H) homeostasis. In conclusion, NADKs, MESH1, and NOCT are integral to various cellular processes, regulating NAD(H) and NADP(H) homeostasis. Dysregulation of these enzymes results in various human diseases, such as cancers and metabolic disorders. Hence, strategies aiming to restore NAD(H) and NADP(H) homeostasis hold promise as novel therapeutic approaches for these diseases.

Keywords:  MESH1; NAD(H); NADK; NADP(H); Nocturnin

DOI:  https://doi.org/10.1016/j.gendis.2023.101146
Front Immunol. 2024 ;15 1400431

Mitophagy and clear cell renal cell carcinoma: insights from single-cell and spatial transcriptomics analysis.

Lai Jiang, Xing Ren, Jinyan Yang, Haiqing Chen, Shengke Zhang, Xuancheng Zhou, Jinbang Huang, Chenglu Jiang, Yuheng Gu, Jingyi Tang, Guanhu Yang, Hao Chi, Jianhua Qin.

   Background: Clear Cell Renal Cell Carcinoma (ccRCC) is the most common type of kidney cancer, characterized by high heterogeneity and complexity. Recent studies have identified mitochondrial defects and autophagy as key players in the development of ccRCC. This study aims to delve into the changes in mitophagic activity within ccRCC and its impact on the tumor microenvironment, revealing its role in tumor cell metabolism, development, and survival strategies.
Methods: Comprehensive analysis of ccRCC tumor tissues using single cell sequencing and spatial transcriptomics to reveal the role of mitophagy in ccRCC. Mitophagy was determined to be altered among renal clear cells by gene set scoring. Key mitophagy cell populations and key prognostic genes were identified using NMF analysis and survival analysis approaches. The role of UBB in ccRCC was also demonstrated by in vitro experiments.
Results: Compared to normal kidney tissue, various cell types within ccRCC tumor tissues exhibited significantly increased levels of mitophagy, especially renal clear cells. Key genes associated with increased mitophagy levels, such as UBC, UBA52, TOMM7, UBB, MAP1LC3B, and CSNK2B, were identified, with their high expression closely linked to poor patient prognosis. Particularly, the ubiquitination process involving the UBB gene was found to be crucial for mitophagy and its quality control.
Conclusion: This study highlights the central role of mitophagy and its regulatory factors in the development of ccRCC, revealing the significance of the UBB gene and its associated ubiquitination process in disease progression.

Keywords:  clear cell renal cell carcinoma; metabolic reprogramming; mitochondrial gene defects; mitophagy; multi-omics analysis; non-negative matrix factorization; prognostic analysis

DOI:  https://doi.org/10.3389/fimmu.2024.1400431
STAR Protoc. 2024 Jul 04. pii: S2666-1667(24)00338-1. [Epub ahead of print]5(3): 103173

Protocol for performing metabolic pathway-based subtyping of breast tumors.

Mohammad Askandar Iqbal, Kirk Smith, Prithvi Singh, Shumaila Siddiqui, Sriram Chandrasekaran.

  Here, we present a protocol for analyzing the global metabolic landscape in breast tumors for the purpose of metabolism-based patient stratification. We describe steps for analyzing 1,454 metabolic genes representing 90 metabolic pathways and subjecting them to an algorithm that calculates the deregulation score of 90 pathways in each tumor sample, thus converting gene-level information into pathway-level information. We then detail procedures for performing clustering analysis to identify metabolic subtypes and using machine learning to develop a signature representing each subtype. For complete details on the use and execution of this protocol, please refer to Iqbal et al.1.

Keywords:  cancer; metabolism; systems biology

DOI:  https://doi.org/10.1016/j.xpro.2024.103173
Dev Cell. 2024 Jul 03. pii: S1534-5807(24)00386-1. [Epub ahead of print]

Slc25a3-dependent copper transport controls flickering-induced Opa1 processing for mitochondrial safeguard.

Daisuke Murata, Shubhrajit Roy, Svetlana Lutsenko, Miho Iijima, Hiromi Sesaki.

  Following the Goldilocks principle, mitochondria size must be "just right." Mitochondria balance division and fusion to avoid becoming too big or too small. Defects in this balance produce dysfunctional mitochondria in human diseases. Mitochondrial safeguard (MitoSafe) is a defense mechanism that protects mitochondria against extreme enlarging by suppressing fusion in mammalian cells. In MitoSafe, hyperfused mitochondria elicit flickering-short pulses of mitochondrial depolarization. Flickering activates an inner membrane protease, Oma1, which in turn proteolytically inactivates a mitochondrial fusion protein, Opa1. The mechanisms underlying flickering are unknown. Using a live-imaging screen, we identified Slc25a3 (a mitochondrial carrier transporting phosphate and copper) as necessary for flickering and Opa1 cleavage. Remarkably, copper, but not phosphate, is critical for flickering. Furthermore, we found that two copper-containing mitochondrial enzymes, superoxide dismutase 1 and cytochrome c oxidase, regulate flickering. Our data identify an unforeseen mechanism linking copper, redox homeostasis, and membrane flickering in mitochondrial defense against deleterious fusion.

Keywords:  division; fusion; mitochondria; stress response; transporter

DOI:  https://doi.org/10.1016/j.devcel.2024.06.008
Nat Commun. 2024 Jul 12. 15(1): 5857

Glucose-6-phosphate dehydrogenase maintains redox homeostasis and biosynthesis in LKB1-deficient KRAS-driven lung cancer.

Taijin Lan, Sara Arastu, Jarrick Lam, Hyungsin Kim, Wenping Wang, Samuel Wang, Vrushank Bhatt, Eduardo Cararo Lopes, Zhixian Hu, Michael Sun, Xuefei Luo, Jonathan M Ghergurovich, Xiaoyang Su, Joshua D Rabinowitz, Eileen White, Jessie Yanxiang Guo.

Cancer cells depend on nicotinamide adenine dinucleotide phosphate (NADPH) to combat oxidative stress and support reductive biosynthesis. One major NADPH production route is the oxidative pentose phosphate pathway (committed step: glucose-6-phosphate dehydrogenase, G6PD). Alternatives exist and can compensate in some tumors. Here, using genetically-engineered lung cancer mouse models, we show that G6PD ablation significantly suppresses KrasG12D/+;Lkb1-/- (KL) but not KrasG12D/+;P53-/- (KP) lung tumorigenesis. In vivo isotope tracing and metabolomics reveal that G6PD ablation significantly impairs NADPH generation, redox balance, and de novo lipogenesis in KL but not KP lung tumors. Mechanistically, in KL tumors, G6PD ablation activates p53, suppressing tumor growth. As tumors progress, G6PD-deficient KL tumors increase an alternative NADPH source from serine-driven one carbon metabolism, rendering associated tumor-derived cell lines sensitive to serine/glycine depletion. Thus, oncogenic driver mutations determine lung cancer dependence on G6PD, whose targeting is a potential therapeutic strategy for tumors harboring KRAS and LKB1 co-mutations.

DOI: https://doi.org/10.1038/s41467-024-50157-8
bioRxiv. 2024 Jun 28. pii: 2024.06.23.598940. [Epub ahead of print]

Restoring hippocampal glucose metabolism rescues cognition across Alzheimer's disease pathologies.

Paras S Minhas, Jeffrey R Jones, Amira Latif-Hernandez, Yuki Sugiura, Aarooran S Durairaj, Takeshi Uenaka, Qian Wang, Siddhita D Mhatre, Ling Liu, Travis Conley, Hannah Ennerfelt, Yoo Jin Jung, Praveena Prasad, Brenita C Jenkins, Ryan Goodman, Traci Newmeyer, Kelly Heard, Austin Kang, Edward N Wilson, Erik M Ullian, Geidy E Serrano, Thomas G Beach, Joshua D Rabinowitz, Marius Wernig, Makoto Suematsu, Frank M Longo, Melanie R McReynolds, Fred H Gage, Katrin I Andreasson.

Impaired cerebral glucose metabolism is a pathologic feature of Alzheimer Disease (AD), and recent proteomic studies highlight a disruption of glial carbohydrate metabolism with disease progression. Here, we report that inhibition of indoleamine-2,3-dioxygenase 1 (IDO1), which metabolizes tryptophan to kynurenine (KYN) in the first step of the kynurenine pathway, rescues hippocampal memory function and plasticity in preclinical models of amyloid and tau pathology by restoring astrocytic metabolic support of neurons. Activation of IDO1 in astrocytes by amyloid-beta 42 and tau oligomers, two major pathological effectors in AD, increases KYN and suppresses glycolysis in an AhR-dependent manner. Conversely, pharmacological IDO1 inhibition restores glycolysis and lactate production. In amyloid-producing APP Swe -PS1 ΔE9 and 5XFAD mice and in tau-producing P301S mice, IDO1 inhibition restores spatial memory and improves hippocampal glucose metabolism by metabolomic and MALDI-MS analyses. IDO1 blockade also rescues hippocampal long-term potentiation (LTP) in a monocarboxylate transporter (MCT)-dependent manner, suggesting that IDO1 activity disrupts astrocytic metabolic support of neurons. Indeed, in vitro mass-labeling of human astrocytes demonstrates that IDO1 regulates astrocyte generation of lactate that is then taken up by human neurons. In co-cultures of astrocytes and neurons derived from AD subjects, deficient astrocyte lactate transfer to neurons was corrected by IDO1 inhibition, resulting in improved neuronal glucose metabolism. Thus, IDO1 activity disrupts astrocytic metabolic support of neurons across both amyloid and tau pathologies and in a model of AD iPSC-derived neurons. These findings also suggest that IDO1 inhibitors developed for adjunctive therapy in cancer could be repurposed for treatment of amyloid- and tau-mediated neurodegenerative diseases.

DOI: https://doi.org/10.1101/2024.06.23.598940
Nat Commun. 2024 Jul 10. 15(1): 5818

Compartmentalized mitochondrial ferroptosis converges with optineurin-mediated mitophagy to impact airway epithelial cell phenotypes and asthma outcomes.

Kazuhiro Yamada, Claudette St Croix, Donna B Stolz, Yulia Y Tyurina, Vladimir A Tyurin, Laura R Bradley, Alexander A Kapralov, Yanhan Deng, Xiuxia Zhou, Qi Wei, Bo Liao, Nobuhiko Fukuda, Mara Sullivan, John Trudeau, Anuradha Ray, Valerian E Kagan, Jinming Zhao, Sally E Wenzel.

A stable mitochondrial pool is crucial for healthy cell function and survival. Altered redox biology can adversely affect mitochondria through induction of a variety of cell death and survival pathways, yet the understanding of mitochondria and their dysfunction in primary human cells and in specific disease states, including asthma, is modest. Ferroptosis is traditionally considered an iron dependent, hydroperoxy-phospholipid executed process, which induces cytosolic and mitochondrial damage to drive programmed cell death. However, in this report we identify a lipoxygenase orchestrated, compartmentally-targeted ferroptosis-associated peroxidation process which occurs in a subpopulation of dysfunctional mitochondria, without promoting cell death. Rather, this mitochondrial peroxidation process tightly couples with PTEN-induced kinase (PINK)-1(PINK1)-Parkin-Optineurin mediated mitophagy in an effort to preserve the pool of functional mitochondria and prevent cell death. These combined peroxidation processes lead to altered epithelial cell phenotypes and loss of ciliated cells which associate with worsened asthma severity. Ferroptosis-targeted interventions of this process could preserve healthy mitochondria, reverse cell phenotypic changes and improve disease outcomes.

DOI: https://doi.org/10.1038/s41467-024-50222-2
bioRxiv. 2024 Jun 29. pii: 2024.05.21.594886. [Epub ahead of print]

Genetically Encoded and Modular SubCellular Organelle Probes (GEM-SCOPe) reveal lysosomal and mitochondrial dysfunction driven by PRKN knockout.

Camille Goldman, Tatyana Kareva, Lily Sarrafha, Braxton R Schuldt, Abhishek Sahasrabudhe, Tim Ahfeldt, Joel W Blanchard.

Cellular processes including lysosomal and mitochondrial dysfunction are implicated in the development of many diseases. Quantitative visualization of mitochondria and lysosoesl is crucial to understand how these organelles are dysregulated during disease. To address a gap in live-imaging tools, we developed GEM-SCOPe (Genetically Encoded and Modular SubCellular Organelle Probes), a modular toolbox of fluorescent markers designed to inform on localization, distribution, turnover, and oxidative stress of specific organelles. We expressed GEM-SCOPe in differentiated astrocytes and neurons from a human pluripotent stem cell PRKN- knockout model of Parkinson's disease and identified disease-associated changes in proliferation, lysosomal distribution, mitochondrial transport and turnover, and reactive oxygen species. We demonstrate GEM-SCOPe is a powerful panel that provide critical insight into the subcellular mechanisms underlying Parkinson's disease in human cells. GEM-SCOPe can be expanded upon and applied to a diversity of cellular models to glean an understanding of the mechanisms that promote disease onset and progression.

DOI: https://doi.org/10.1101/2024.05.21.594886
Mol Metab. 2024 Jul 04. pii: S2212-8778(24)00112-1. [Epub ahead of print] 101981

Metabolic profiling of single cells by exploiting NADH and FAD fluorescence via flow cytometry.

Ariful Haque Abir, Leonie Weckwerth, Artur Wilhelm, Jana Thomas, Clara M Reichardt, Luis Munoz, Simon Völkl, Uwe Appelt, Markus Mroz, Raluca Niesner, Anja Hauser, Rebecca Sophie Fischer, Katharina Pracht, Hans-Martin Jäck, Georg Schett, Gerhard Krönke, Dirk Mielenz.

  The metabolism of different cells within the same microenvironment can differ and dictate physiological or pathological adaptions. Current single-cell analysis methods of metabolism are not label-free. The study introduces a label-free, live-cell analysis method assessing endogenous fluorescence of NAD(P)H and FAD in surface-stained cells by flow cytometry. OxPhos inhibition, mitochondrial uncoupling, glucose exposure, genetic inactivation of glucose uptake and mitochondrial respiration alter the optical redox ratios of FAD and NAD(P)H as measured by flow cytometry. Those alterations correlate strongly with measurements obtained by extracellular flux analysis. Consequently, metabolically distinct live B-cell populations can be resolved, showing that human memory B-cells from peripheral blood exhibit a higher glycolytic flexibility than naïve B cells. Moreover, the comparison of blood-derived B- and T-lymphocytes from healthy donors and rheumatoid arthritis patients unleashes rheumatoid arthritis-associated metabolic traits in human naïve and memory B-lymphocytes. Taken together, these data show that the optical redox ratio can depict metabolic differences in distinct cell populations by flow cytometry.

Keywords:  FAD; Flow cytometry; Fluorescence; Metabolism; NADH; Real-time

DOI:  https://doi.org/10.1016/j.molmet.2024.101981
Int J Mol Sci. 2024 Jun 27. pii: 7037. [Epub ahead of print]25(13):

Origin and Roles of Alanine and Glutamine in Gluconeogenesis in the Liver, Kidneys, and Small Intestine under Physiological and Pathological Conditions.

Milan Holeček.

  Alanine and glutamine are the principal glucogenic amino acids. Most originate from muscles, where branched-chain amino acids (valine, leucine, and isoleucine) are nitrogen donors and, under exceptional circumstances, a source of carbons for glutamate synthesis. Glutamate is a nitrogen source for alanine synthesis from pyruvate and a substrate for glutamine synthesis by glutamine synthetase. The following differences between alanine and glutamine, which can play a role in their use in gluconeogenesis, are shown: (i) glutamine appearance in circulation is higher than that of alanine; (ii) the conversion to oxaloacetate, the starting substance for glucose synthesis, is an ATP-consuming reaction for alanine, which is energetically beneficial for glutamine; (iii) most alanine carbons, but not glutamine carbons, originate from glucose; and (iv) glutamine acts a substrate for gluconeogenesis in the liver, kidneys, and intestine, whereas alanine does so only in the liver. Alanine plays a significant role during early starvation, exposure to high-fat and high-protein diets, and diabetes. Glutamine plays a dominant role in gluconeogenesis in prolonged starvation, acidosis, liver cirrhosis, and severe illnesses like sepsis and acts as a substrate for alanine synthesis in the small intestine. Interactions among muscles and the liver, kidneys, and intestine ensuring optimal alanine and glutamine supply for gluconeogenesis are suggested.

Keywords:  branched-chain amino acids; cirrhosis; diabetes; glucose; starvation

DOI:  https://doi.org/10.3390/ijms25137037
Trends Endocrinol Metab. 2024 Jul 06. pii: S1043-2760(24)00168-1. [Epub ahead of print]

Interorganelle phospholipid communication, a house not so divided.

Richard G Lee, Danielle L Rudler, Oliver Rackham, Aleksandra Filipovska.

  The presence of membrane-bound organelles with specific functions is one of the main hallmarks of eukaryotic cells. Organelle membranes are composed of specific lipids that govern their function and interorganelle communication. Discoveries in cell biology using imaging and omic technologies have revealed the mechanisms that drive membrane remodeling, organelle contact sites, and metabolite exchange. The interplay between multiple organelles and their interdependence is emerging as the next frontier for discovery using 3D reconstruction of volume electron microscopy (vEM) datasets. We discuss recent findings on the links between organelles that underlie common functions and cellular pathways. Specifically, we focus on the metabolism of ether glycerophospholipids that mediate organelle dynamics and their communication with each other, and the new imaging techniques that are powering these discoveries.

Keywords:  metabolic diseases; mitochondria; organelles; volume electron microscopy

DOI:  https://doi.org/10.1016/j.tem.2024.06.008
Autophagy. 2024 Jul 10. 1-7

Let's talk about flux: the rising potential of autophagy rate measurements in disease.

Nitin Sai Beesabathuni, Matthew W Kenaston, Ritika Gangaraju, Neil Alvin B Adia, Vardhan Peddamallu, Priya S Shah.

  Macroautophagy/autophagy is increasingly implicated in a variety of diseases, making it an attractive therapeutic target. However, many aspects of autophagy are not fully understood and its impact on many diseases remains debatable and context-specific. The lack of systematic and dynamic measurements in these cases is a key reason for this ambiguity. In recent years, Loos et al. 2014 and Beesabathuni et al. 2022 developed methods to quantitatively measure autophagy holistically. In this commentary, we pose some of the unresolved biological questions regarding autophagy and consider how quantitative measurements may address them. While the applications are ever-expanding, we provide specific use cases in cancer, virus infection, and mechanistic screening. We address how the rate measurements themselves are central to developing cancer therapies and present ways in which these tools can be leveraged to dissect the complexities of virus-autophagy interactions. Screening methods can be combined with rate measurements to mechanistically decipher the labyrinth of autophagy regulation in cancer and virus infection. Taken together, these approaches have the potential to illuminate the underlying mechanisms of various diseases.Abbreviation MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; R1: rate of autophagosome formation; R2: rate of autophagosome-lysosome fusion; R3: rate of autolysosome turnover.

Keywords:  Autophagy flux; autophagy perturbation; autophagy temporal dynamics; autophagy-dependent cell death; cancer; virus infection

DOI:  https://doi.org/10.1080/15548627.2024.2371708
Mol Cell. 2024 Jul 11. pii: S1097-2765(24)00522-7. [Epub ahead of print]84(13): 2407-2409

Thrifty tissues prefer recycled purines over new-cleotides.

David Sokolov, Lucas B Sullivan.

In two recent studies appearing in Cell1 and Cell Metabolism,2 Tran et al. and Wu et al. describe underappreciated nuance in organismal and cellular purine nucleotide salvage pathways and identify purine salvage as a metabolic limitation for tumor growth.

DOI: https://doi.org/10.1016/j.molcel.2024.06.015
bioRxiv. 2024 Jun 28. pii: 2024.06.23.600101. [Epub ahead of print]

Phosphoglycerate mutase regulates Treg differentiation through control of serine synthesis and one-carbon metabolism.

Wesley H Godfrey, Kaho Cho, Xiaojing Deng, Chandra Shekar R Ambati, Vasanta Putluri, Abu Hena Mostafa Kamal, Nagireddy Putluri, Michael D Kornberg.

The differentiation and suppressive functions of regulatory CD4 T cells (Tregs) are supported by a broad array of metabolic changes, providing potential therapeutic targets for immune modulation. In this study, we focused on the regulatory role of glycolytic enzymes in Tregs and identified phosphoglycerate mutase (PGAM) as being differentially overexpressed in Tregs and associated with a highly suppressive phenotype. Pharmacologic or genetic inhibition of PGAM reduced Treg differentiation and suppressive function while reciprocally inducing markers of a pro-inflammatory, T helper 17 (Th17)-like state. The regulatory role of PGAM was dependent on the contribution of 3-phosphoglycerate (3PG), the PGAM substrate, to de novo serine synthesis. Blocking de novo serine synthesis from 3PG reversed the effect of PGAM inhibition on Treg polarization, while exogenous serine directly inhibited Treg polarization. Additionally, altering serine levels in vivo with a serine/glycine-free diet increased peripheral Tregs and attenuated autoimmunity in a murine model of multiple sclerosis. Mechanistically, we found that serine limits Treg polarization by contributing to one-carbon metabolism and methylation of Treg-associated genes. Inhibiting one-carbon metabolism increased Treg polarization and suppressive function both in vitro and in vivo in a murine model of autoimmune colitis. Our study identifies a novel physiologic role for PGAM and highlights the metabolic interconnectivity between glycolysis, serine synthesis, one-carbon metabolism, and epigenetic regulation of Treg differentiation and suppressive function.

DOI: https://doi.org/10.1101/2024.06.23.600101
Acta Histochem Cytochem. 2024 Jun 28. 57(3): 89-100

Purinosomes and Purine Metabolism in Mammalian Neural Development: A Review.

Seiya Yamada, Tomoya Mizukoshi, Ayaka Sato, Shin-Ichi Sakakibara.

  Neural stem/progenitor cells (NSPCs) in specific brain regions require precisely regulated metabolite production during critical development periods. Purines-vital components of DNA, RNA, and energy carriers like ATP and GTP-are crucial metabolites in brain development. Purine levels are tightly controlled through two pathways: de novo synthesis and salvage synthesis. Enzymes driving de novo pathway are assembled into a large multienzyme complex termed the "purinosome." Here, we review purine metabolism and purinosomes as spatiotemporal regulators of neural development. Notably, around postnatal day 0 (P0) during mouse cortical development, purine synthesis transitions from the de novo pathway to the salvage pathway. Inhibiting the de novo pathway affects mTORC1 pathway and leads to specific forebrain malformations. In this review, we also explore the importance of protein-protein interactions of a newly identified NSPC protein-NACHT and WD repeat domain-containing 1 (Nwd1)-in purinosome formation. Reduced Nwd1 expression disrupts purinosome formation, impacting NSPC proliferation and neuronal migration, resulting in periventricular heterotopia. Nwd1 interacts directly with phosphoribosylaminoimidazole-succinocarboxamide synthetase (PAICS), an enzyme involved in de novo purine synthesis. We anticipate this review will be valuable for researchers investigating neural development, purine metabolism, and protein-protein interactions.

Keywords:  Nwd1; neural development; neural stem/progenitor cells (NSPCs); purine metabolism; purinosome

DOI:  https://doi.org/10.1267/ahc.24-00027
Int J Mol Sci. 2024 Jul 06. pii: 7441. [Epub ahead of print]25(13):

The Protective Effect of Uridine in a Rotenone-Induced Model of Parkinson's Disease: The Role of the Mitochondrial ATP-Dependent Potassium Channel.

Galina D Mironova, Alexei A Mosentsov, Vasilii V Mironov, Vasilisa P Medvedeva, Natalia V Khunderyakova, Lyubov L Pavlik, Irina B Mikheeva, Maria I Shigaeva, Alexey V Agafonov, Natalya V Khmil, Natalia V Belosludtseva.

  The effect of the modulators of the mitochondrial ATP-dependent potassium channel (mitoKATP) on the structural and biochemical alterations in the substantia nigra and brain tissues was studied in a rat model of Parkinson's disease induced by rotenone. It was found that, in experimental parkinsonism accompanied by characteristic motor deficits, both neurons and the myelin sheath of nerve fibers in the substantia nigra were affected. Changes in energy and ion exchange in brain mitochondria were also revealed. The nucleoside uridine, which is a source for the synthesis of the mitoKATP channel opener uridine diphosphate, was able to dose-dependently decrease behavioral disorders and prevent the death of animals, which occurred for about 50% of animals in the model. Uridine prevented disturbances in redox, energy, and ion exchanges in brain mitochondria, and eliminated alterations in their structure and the myelin sheath in the substantia nigra. Cytochemical examination showed that uridine restored the indicators of oxidative phosphorylation and glycolysis in peripheral blood lymphocytes. The specific blocker of the mitoKATP channel, 5-hydroxydecanoate, eliminated the positive effects of uridine, suggesting that this channel is involved in neuroprotection. Taken together, these findings indicate the promise of using the natural metabolite uridine as a new drug to prevent and, possibly, stop the progression of Parkinson's disease.

Keywords:  Parkinson’s disease; mitochondria; mitochondrial ATP-dependent potassium channel; myeline; neurons; oxidative stress; rotenone; structure; uridine

DOI:  https://doi.org/10.3390/ijms25137441
Nat Commun. 2024 Jul 08. 15(1): 5715

Egg multivesicular bodies elicit an LC3-associated phagocytosis-like pathway to degrade paternal mitochondria after fertilization.

Sharon Ben-Hur, Shoshana Sernik, Sara Afar, Alina Kolpakova, Yoav Politi, Liron Gal, Anat Florentin, Ofra Golani, Ehud Sivan, Nili Dezorella, David Morgenstern, Shmuel Pietrokovski, Eyal Schejter, Keren Yacobi-Sharon, Eli Arama.

Mitochondria are maternally inherited, but the mechanisms underlying paternal mitochondrial elimination after fertilization are far less clear. Using Drosophila, we show that special egg-derived multivesicular body vesicles promote paternal mitochondrial elimination by activating an LC3-associated phagocytosis-like pathway, a cellular defense pathway commonly employed against invading microbes. Upon fertilization, these egg-derived vesicles form extended vesicular sheaths around the sperm flagellum, promoting degradation of the sperm mitochondrial derivative and plasma membrane. LC3-associated phagocytosis cascade of events, including recruitment of a Rubicon-based class III PI(3)K complex to the flagellum vesicular sheaths, its activation, and consequent recruitment of Atg8/LC3, are all required for paternal mitochondrial elimination. Finally, lysosomes fuse with strings of large vesicles derived from the flagellum vesicular sheaths and contain degrading fragments of the paternal mitochondrial derivative. Given reports showing that in some mammals, the paternal mitochondria are also decorated with Atg8/LC3 and surrounded by multivesicular bodies upon fertilization, our findings suggest that a similar pathway also mediates paternal mitochondrial elimination in other flagellated sperm-producing organisms.

DOI: https://doi.org/10.1038/s41467-024-50041-5
Nat Commun. 2024 Jul 09. 15(1): 5759

Metabolic reprograming mediated by tumor cell-intrinsic type I IFN signaling is required for CD47-SIRPα blockade efficacy.

Hang Zhou, Wenjun Wang, Hairong Xu, Yong Liang, Jiyu Ding, Mengjie Lv, Boyang Ren, Hua Peng, Yang-Xin Fu, Mingzhao Zhu.

Type I interferons have been well recognized for their roles in various types of immune cells during tumor immunotherapy. However, their direct effects on tumor cells are less understood. Oxidative phosphorylation is typically latent in tumor cells. Whether oxidative phosphorylation can be targeted for immunotherapy remains unclear. Here, we find that tumor cell responsiveness to type I, but not type II interferons, is essential for CD47-SIRPα blockade immunotherapy in female mice. Mechanistically, type I interferons directly reprogram tumor cell metabolism by activating oxidative phosphorylation for ATP production in an ISG15-dependent manner. ATP extracellular release is also promoted by type I interferons due to enhanced secretory autophagy. Functionally, tumor cells with genetic deficiency in oxidative phosphorylation or autophagy are resistant to CD47-SIRPα blockade. ATP released upon CD47-SIRPα blockade is required for antitumor T cell response induction via P2X7 receptor-mediated dendritic cell activation. Based on this mechanism, combinations with inhibitors of ATP-degrading ectoenzymes, CD39 and CD73, are designed and show synergistic antitumor effects with CD47-SIRPα blockade. Together, these data reveal an important role of type I interferons on tumor cell metabolic reprograming for tumor immunotherapy and provide rational strategies harnessing this mechanism for enhanced efficacy of CD47-SIRPα blockade.

DOI: https://doi.org/10.1038/s41467-024-50136-z
bioRxiv. 2024 Jun 27. pii: 2024.06.22.600201. [Epub ahead of print]

Coordinated Regulation of Renal Glucose Reabsorption and Gluconeogenesis by mTORC2 and Potassium.

John Demko, Bidisha Saha, Enzo Takagi, Anna Mannis, Robert Weber, David Pearce.

Background: The kidney proximal tubule is uniquely responsible for reabsorption of filtered glucose and gluconeogenesis (GNG). Insulin stimulates glucose transport and suppresses GNG in the proximal tubule, however, the signaling mechanisms and coordinated regulation of these processes remain poorly understood. The kinase complex mTORC2 is critical for regulation of growth, metabolism, solute transport, and electrolyte homeostasis in response to a wide array of inputs. Here we examined its role in the regulation of renal glucose reabsorption and GNG.
Methods: Rictor, an essential component of mTORC2, was knocked out using the Pax8-LC1 system to generate inducible tubule specific Rictor knockout (TRKO) mice. These animals were subjected to fasting, refeeding, and variation in dietary K + . Metabolic parameters including glucose homeostasis and renal function were assessed in balance cages. Kidneys and livers were also harvested for molecular analysis of gluconeogenic enzymes, mTORC2-regulated targets, and plasma membrane glucose transporters.
Results: On a normal chow diet, TRKO mice had marked glycosuria despite indistinguishable blood glucose relative to WT controls. Kidney plasma membrane showed lower SGLT2 and SGLT1 in the fed state, supporting reduced renal glucose reabsorption. Additional metabolic testing provided evidence for renal insulin resistance with elevated fasting insulin, impaired pyruvate tolerance, elevated hemoglobin A1c, and increased renal gluconeogenic enzymes in the fasted and fed states. These effects were correlated with reduced downstream phosphorylation of Akt and the transcription factor FOXO4, identifying a novel role of FOXO4 in the kidney. Interestingly, high dietary K + prevented glycosuria and excessive GNG in TRKO mice, despite persistent reduction in mTORC2 substrate phosphorylation.
Conclusion: Renal tubule mTORC2 is critical for coordinated regulation of sodium-glucose cotransport by SGLT2 and SGLT1 as well as renal GNG. Dietary K + promotes glucose reabsorption and suppresses GNG independently of insulin signaling and mTORC2, potentially providing an alternative signaling mechanism in states of insulin resistance.
SIGNIFICANCE STATEMENT: The kidney contributes to regulation of blood glucose through reabsorption of filtered glucose and gluconeogenesis. This study shows that mTORC2 and dietary potassium coordinate the regulation of sodium-glucose cotransport and glucose production in the kidney via independent mechanisms. New insights into the regulation of these processes in the kidney offer promising implications for diabetes mellitus management and treatment.

DOI: https://doi.org/10.1101/2024.06.22.600201
Science. 2024 Jul 12. 385(6705): 174-178

Integrated translation and metabolism in a partially self-synthesizing biochemical network.

Simone Giaveri, Nitin Bohra, Christoph Diehl, Hao Yuan Yang, Martine Ballinger, Nicole Paczia, Timo Glatter, Tobias J Erb.

One of the hallmarks of living organisms is their capacity for self-organization and regeneration, which requires a tight integration of metabolic and genetic networks. We sought to construct a linked metabolic and genetic network in vitro that shows such lifelike behavior outside of a cellular context and generates its own building blocks from nonliving matter. We integrated the metabolism of the crotonyl-CoA/ethyl-malonyl-CoA/hydroxybutyryl-CoA cycle with cell-free protein synthesis using recombinant elements. Our network produces the amino acid glycine from CO2 and incorporates it into target proteins following DNA-encoded instructions. By orchestrating ~50 enzymes we established a basic cell-free operating system in which genetically encoded inputs into a metabolic network are programmed to activate feedback loops allowing for self-integration and (partial) self-regeneration of the complete system.

DOI: https://doi.org/10.1126/science.adn3856
PLoS Pathog. 2024 Jul 08. 20(7): e1011909

Norovirus NS1/2 protein increases glutaminolysis for efficient viral replication.

Adam Hafner, Noah Meurs, Ari Garner, Elaine Azar, Aditya Kannan, Karla D Passalacqua, Deepak Nagrath, Christiane E Wobus.

Viruses are obligate intracellular parasites that rely on host cell metabolism for successful replication. Thus, viruses rewire host cell pathways involved in central carbon metabolism to increase the availability of building blocks for successful propagation. However, the underlying mechanisms of virus-induced alterations to host metabolism are largely unknown. Noroviruses (NoVs) are highly prevalent pathogens that cause sporadic and epidemic viral gastroenteritis. In the present study, we uncovered several strain-specific and shared host cell metabolic requirements of three murine norovirus (MNV) strains, MNV-1, CR3, and CR6. While all three strains required glycolysis, glutaminolysis, and the pentose phosphate pathway for optimal infection of macrophages, only MNV-1 relied on host oxidative phosphorylation. Furthermore, the first metabolic flux analysis of NoV-infected cells revealed that both glycolysis and glutaminolysis are upregulated during MNV-1 infection of macrophages. Glutamine deprivation affected the viral lifecycle at the stage of genome replication, resulting in decreased non-structural and structural protein synthesis, viral assembly, and egress. Mechanistic studies further showed that MNV infection and overexpression of the non-structural protein NS1/2 increased the enzymatic activity of the rate-limiting enzyme glutaminase. In conclusion, the inaugural investigation of NoV-induced alterations to host glutaminolysis identified NS1/2 as the first viral molecule for RNA viruses that regulates glutaminolysis either directly or indirectly. This increases our fundamental understanding of virus-induced metabolic alterations and may lead to improvements in the cultivation of human NoVs.

DOI: https://doi.org/10.1371/journal.ppat.1011909