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1.
Int J Mol Sci ; 23(9)2022 Apr 28.
Article in English | MEDLINE | ID: covidwho-1847341

ABSTRACT

Obesity is a leading cause of preventable death and morbidity. To elucidate the mechanisms connecting metabolically active brown adipose tissue (BAT) and metabolic health may provide insights into methods of treatment for obesity-related conditions. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18FDG-PET/CT) is traditionally used to image human BAT activity. However, the primary energy source of BAT is derived from intracellular fatty acids and not glucose. Beta-methyl-p-iodophenylpentadecanoic acid (BMIPP) is a fatty acid analogue amenable to in vivo imaging by single photon emission computed tomography/CT (SPECT/CT) when radiolabeled with iodine isotopes. In this study, we compare the use of 18FDG-PET/CT and 125I-BMIPP-SPECT/CT for fat imaging to ascertain whether BMIPP is a more robust candidate for the non-invasive evaluation of metabolically active adipose depots. Interscapular BAT, inguinal white adipose tissue (iWAT), and gonadal white adipose tissue (gWAT) uptake of 18FDG and 125I-BMIPP was quantified in mice following treatment with the BAT-stimulating drug CL-316,243 or saline vehicle control. After CL-316,243 treatment, uptake of both radiotracers increased in BAT and iWAT. The standard uptake value (SUVmean) for 18FDG and 125I-BMIPP significantly correlated in these depots, although uptake of 125I-BMIPP in BAT and iWAT more closely mimicked the fold-change in metabolic rate as measured by an extracellular flux analyzer. Herein, we find that imaging BAT with the radioiodinated fatty acid analogue BMIPP yields more physiologically relevant data than 18FDG-PET/CT, and its conventional use may be a pivotal tool for evaluating BAT in both mice and humans.


Subject(s)
Adipose Tissue, Brown , Fluorodeoxyglucose F18 , Adipose Tissue, Brown/diagnostic imaging , Adipose Tissue, Brown/metabolism , Animals , Fatty Acids/metabolism , Fluorodeoxyglucose F18/metabolism , Iodobenzenes , Mice , Obesity/metabolism , Positron Emission Tomography Computed Tomography , Positron-Emission Tomography , Radiopharmaceuticals/metabolism , Tomography, Emission-Computed, Single-Photon/methods
2.
Int J Mol Sci ; 23(9)2022 May 03.
Article in English | MEDLINE | ID: covidwho-1820295

ABSTRACT

Lipid modification of viral proteins with fatty acids of different lengths (S-acylation) is crucial for virus pathogenesis. The reaction is catalyzed by members of the DHHC family and proceeds in two steps: the autoacylation is followed by the acyl chain transfer onto protein substrates. The crystal structure of human DHHC20 (hDHHC20), an enzyme involved in the acylation of S-protein of SARS-CoV-2, revealed that the acyl chain may be inserted into a hydrophobic cavity formed by four transmembrane (TM) α-helices. To test this model, we used molecular dynamics of membrane-embedded hDHHC20 and its mutants either in the absence or presence of various acyl-CoAs. We found that among a range of acyl chain lengths probed only C16 adopts a conformation suitable for hDHHC20 autoacylation. This specificity is altered if the small or bulky residues at the cavity's ceiling are exchanged, e.g., the V185G mutant obtains strong preferences for binding C18. Surprisingly, an unusual hydrophilic ridge was found in TM helix 4 of hDHHC20, and the responsive hydrophilic patch supposedly involved in association was found in the 3D model of the S-protein TM-domain trimer. Finally, the exchange of critical Thr and Ser residues in the spike led to a significant decrease in its S-acylation. Our data allow further development of peptide/lipid-based inhibitors of hDHHC20 that might impede replication of Corona- and other enveloped viruses.


Subject(s)
Acyltransferases , COVID-19 , Acyl Coenzyme A/metabolism , Acylation , Acyltransferases/chemistry , Acyltransferases/metabolism , Fatty Acids/chemistry , Fatty Acids/metabolism , Humans , Molecular Dynamics Simulation , SARS-CoV-2 , Substrate Specificity/physiology
3.
Nat Commun ; 13(1): 868, 2022 02 14.
Article in English | MEDLINE | ID: covidwho-1684025

ABSTRACT

SARS-CoV-2 infection is a major global public health concern with incompletely understood pathogenesis. The SARS-CoV-2 spike (S) glycoprotein comprises a highly conserved free fatty acid binding pocket (FABP) with unknown function and evolutionary selection advantage1,2. Deciphering FABP impact on COVID-19 progression is challenged by the heterogenous nature and large molecular variability of live virus. Here we create synthetic minimal virions (MiniVs) of wild-type and mutant SARS-CoV-2 with precise molecular composition and programmable complexity by bottom-up assembly. MiniV-based systematic assessment of S free fatty acid (FFA) binding reveals that FABP functions as an allosteric regulatory site enabling adaptation of SARS-CoV-2 immunogenicity to inflammation states via binding of pro-inflammatory FFAs. This is achieved by regulation of the S open-to-close equilibrium and the exposure of both, the receptor binding domain (RBD) and the SARS-CoV-2 RGD motif that is responsible for integrin co-receptor engagement. We find that the FDA-approved drugs vitamin K and dexamethasone modulate S-based cell binding in an FABP-like manner. In inflammatory FFA environments, neutralizing immunoglobulins from human convalescent COVID-19 donors lose neutralization activity. Empowered by our MiniV technology, we suggest a conserved mechanism by which SARS-CoV-2 dynamically couples its immunogenicity to the host immune response.


Subject(s)
COVID-19/immunology , Fatty Acids/immunology , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Virion/immunology , A549 Cells , Allosteric Site/genetics , Amino Acid Sequence , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Binding Sites/genetics , COVID-19/metabolism , COVID-19/virology , Cells, Cultured , Cryoelectron Microscopy/methods , Electron Microscope Tomography/methods , Fatty Acid-Binding Proteins/immunology , Fatty Acid-Binding Proteins/metabolism , Fatty Acids/metabolism , Humans , MCF-7 Cells , Microscopy, Confocal/methods , Protein Binding , SARS-CoV-2/metabolism , SARS-CoV-2/physiology , Sequence Homology, Amino Acid , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism , Virion/metabolism , Virion/ultrastructure
5.
Front Immunol ; 12: 784989, 2021.
Article in English | MEDLINE | ID: covidwho-1603282

ABSTRACT

Effective treatment strategies for severe coronavirus disease (COVID-19) remain scarce. Hydrolysis of membrane-embedded, inert sphingomyelin by stress responsive sphingomyelinases is a hallmark of adaptive responses and cellular repair. As demonstrated in experimental and observational clinical studies, the transient and stress-triggered release of a sphingomyelinase, SMPD1, into circulation and subsequent ceramide generation provides a promising target for FDA-approved drugs. Here, we report the activation of sphingomyelinase-ceramide pathway in 23 intensive care patients with severe COVID-19. We observed an increase of circulating activity of sphingomyelinase with subsequent derangement of sphingolipids in serum lipoproteins and from red blood cells (RBC). Consistent with increased ceramide levels derived from the inert membrane constituent sphingomyelin, increased activity of acid sphingomyelinase (ASM) accurately distinguished the patient cohort undergoing intensive care from healthy controls. Positive correlational analyses with biomarkers of severe clinical phenotype support the concept of an essential pathophysiological role of ASM in the course of SARS-CoV-2 infection as well as of a promising role for functional inhibition with anti-inflammatory agents in SARS-CoV-2 infection as also proposed in independent observational studies. We conclude that large-sized multicenter, interventional trials are now needed to evaluate the potential benefit of functional inhibition of this sphingomyelinase in critically ill patients with COVID-19.


Subject(s)
COVID-19/metabolism , Ceramides/metabolism , Signal Transduction , Sphingomyelin Phosphodiesterase/metabolism , Anti-Inflammatory Agents/therapeutic use , COVID-19/drug therapy , COVID-19/virology , Ceramides/blood , Enzyme Activation , Erythrocyte Membrane/metabolism , Erythrocytes/metabolism , Fatty Acids/metabolism , Humans , Intensive Care Units , Patient Acuity , SARS-CoV-2/drug effects , SARS-CoV-2/physiology , Sphingomyelin Phosphodiesterase/blood , Sphingomyelins/metabolism
6.
J Clin Invest ; 131(22)2021 11 15.
Article in English | MEDLINE | ID: covidwho-1518200

ABSTRACT

Metabolic pathways regulate immune responses and disrupted metabolism leads to immune dysfunction and disease. Coronavirus disease 2019 (COVID-19) is driven by imbalanced immune responses, yet the role of immunometabolism in COVID-19 pathogenesis remains unclear. By investigating 87 patients with confirmed SARS-CoV-2 infection, 6 critically ill non-COVID-19 patients, and 47 uninfected controls, we found an immunometabolic dysregulation in patients with progressed COVID-19. Specifically, T cells, monocytes, and granulocytes exhibited increased mitochondrial mass, yet only T cells accumulated intracellular reactive oxygen species (ROS), were metabolically quiescent, and showed a disrupted mitochondrial architecture. During recovery, T cell ROS decreased to match the uninfected controls. Transcriptionally, T cells from severe/critical COVID-19 patients showed an induction of ROS-responsive genes as well as genes related to mitochondrial function and the basigin network. Basigin (CD147) ligands cyclophilin A and the SARS-CoV-2 spike protein triggered ROS production in T cells in vitro. In line with this, only PCR-positive patients showed increased ROS levels. Dexamethasone treatment resulted in a downregulation of ROS in vitro and T cells from dexamethasone-treated patients exhibited low ROS and basigin levels. This was reflected by changes in the transcriptional landscape. Our findings provide evidence of an immunometabolic dysregulation in COVID-19 that can be mitigated by dexamethasone treatment.


Subject(s)
Basigin/physiology , COVID-19/immunology , Dexamethasone/pharmacology , SARS-CoV-2 , T-Lymphocytes/metabolism , Adult , COVID-19/metabolism , Cyclophilin A/physiology , Fatty Acids/metabolism , Female , Humans , Male , Middle Aged , Mitochondria/pathology , Reactive Oxygen Species/metabolism
7.
Int J Mol Sci ; 22(21)2021 Oct 25.
Article in English | MEDLINE | ID: covidwho-1480800

ABSTRACT

Plenty of research has revealed virus induced alternations in metabolic pathways, which is known as metabolic reprogramming. Studies focusing on COVID-19 have uncovered significant changes in metabolism, resulting in the perspective that COVID-19 is a metabolic disease. Reprogramming of amino acid, glucose, cholesterol and fatty acid is distinctive characteristic of COVID-19 infection. These metabolic changes in COVID-19 have a critical role not only in producing energy and virus constituent elements, but also in regulating immune response, offering new insights into COVID-19 pathophysiology. Remarkably, metabolic reprogramming provides great opportunities for developing novel biomarkers and therapeutic agents for COVID-19 infection. Such novel agents are expected to be effective adjuvant therapies. In this review, we integrate present studies about major metabolic reprogramming in COVID-19, as well as the possibility of targeting reprogrammed metabolism to combat virus infection.


Subject(s)
COVID-19/metabolism , COVID-19/virology , Metabolic Networks and Pathways , Amino Acids/metabolism , Cholesterol/metabolism , Fatty Acids/metabolism , Glucose/metabolism , Humans , Hypoxia-Inducible Factor 1/metabolism
8.
J Biol Chem ; 297(5): 101272, 2021 11.
Article in English | MEDLINE | ID: covidwho-1446795

ABSTRACT

Mammalian cells acquire fatty acids (FAs) from dietary sources or via de novo palmitate production by fatty acid synthase (FASN). Although most cells express FASN at low levels, it is upregulated in cancers of the breast, prostate, and liver, among others, and is required during the replication of many viruses, such as dengue virus, hepatitis C, HIV-1, hepatitis B, and severe acute respiratory syndrome coronavirus 2, among others. The precise role of FASN in disease pathogenesis is poorly understood, and whether de novo FA synthesis contributes to host or viral protein acylation has been traditionally difficult to study. Here, we describe a cell-permeable and click chemistry-compatible alkynyl acetate analog (alkynyl acetic acid or 5-hexynoic acid [Alk-4]) that functions as a reporter of FASN-dependent protein acylation. In an FASN-dependent manner, Alk-4 selectively labels the cellular protein interferon-induced transmembrane protein 3 at its known palmitoylation sites, a process that is essential for the antiviral activity of the protein, and the HIV-1 matrix protein at its known myristoylation site, a process that is required for membrane targeting and particle assembly. Alk-4 metabolic labeling also enabled biotin-based purification and identification of more than 200 FASN-dependent acylated cellular proteins. Thus, Alk-4 is a useful bioorthogonal tool to selectively probe FASN-mediated protein acylation in normal and diseased states.


Subject(s)
Fatty Acid Synthase, Type I/metabolism , Acylation , Fatty Acids/metabolism , HEK293 Cells , Humans , SARS-CoV-2/metabolism
9.
Angew Chem Int Ed Engl ; 60(13): 7098-7110, 2021 03 22.
Article in English | MEDLINE | ID: covidwho-1384107

ABSTRACT

We investigate binding of linoleate and other potential ligands to the recently discovered fatty acid binding site in the SARS-CoV-2 spike protein, using docking and molecular dynamics simulations. Simulations suggest that linoleate and dexamethasone stabilize the locked spike conformation, thus reducing the opportunity for ACE2 interaction. In contrast, cholesterol may expose the receptor-binding domain by destabilizing the closed structure, preferentially binding to a different site in the hinge region of the open structure. We docked a library of FDA-approved drugs to the fatty acid site using an approach that reproduces the structure of the linoleate complex. Docking identifies steroids (including dexamethasone and vitamin D); retinoids (some known to be active in vitro, and vitamin A); and vitamin K as potential ligands that may stabilize the closed conformation. The SARS-CoV-2 spike fatty acid site may bind a diverse array of ligands, including dietary components, and therefore provides a promising target for therapeutics or prophylaxis.


Subject(s)
Molecular Dynamics Simulation , Retinoids/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Steroids/metabolism , Vitamins/metabolism , Binding Sites , COVID-19/pathology , COVID-19/virology , Fatty Acids/chemistry , Fatty Acids/metabolism , Humans , Ligands , Molecular Docking Simulation , Protein Structure, Quaternary , Retinoids/chemistry , SARS-CoV-2/isolation & purification , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/chemistry , Steroids/chemistry , Vitamins/chemistry
10.
Int J Mol Sci ; 22(15)2021 Jul 31.
Article in English | MEDLINE | ID: covidwho-1346501

ABSTRACT

17,18-Epoxyeicosatetraenoic acid (17,18-EEQ) and 19,20-epoxydocosapentaenoic acid (19,20-EDP) are bioactive epoxides produced from n-3 polyunsaturated fatty acid eicosapentaenoic acid and docosahexaenoic acid, respectively. However, these epoxides are quickly metabolized into less active diols by soluble epoxide hydrolase (sEH). We have previously demonstrated that an sEH inhibitor, t-TUCB, decreased serum triglycerides (TG) and increased lipid metabolic protein expression in the brown adipose tissue (BAT) of diet-induced obese mice. This study investigates the preventive effects of t-TUCB (T) alone or combined with 19,20-EDP (T + EDP) or 17,18-EEQ (T + EEQ) on BAT activation in the development of diet-induced obesity and metabolic disorders via osmotic minipump delivery in mice. Both T + EDP and T + EEQ groups showed significant improvement in fasting glucose, serum triglycerides, and higher core body temperature, whereas heat production was only significantly increased in the T + EEQ group. Moreover, both the T + EDP and T + EEQ groups showed less lipid accumulation in the BAT. Although UCP1 expression was not changed, PGC1α expression was increased in all three treated groups. In contrast, the expression of CPT1A and CPT1B, which are responsible for the rate-limiting step for fatty acid oxidation, was only increased in the T + EDP and T + EEQ groups. Interestingly, as a fatty acid transporter, CD36 expression was only increased in the T + EEQ group. Furthermore, both the T + EDP and T + EEQ groups showed decreased inflammatory NFκB signaling in the BAT. Our results suggest that 17,18-EEQ or 19,20-EDP combined with t-TUCB may prevent high-fat diet-induced metabolic disorders, in part through increased thermogenesis, upregulating lipid metabolic protein expression, and decreasing inflammation in the BAT.


Subject(s)
Anti-Obesity Agents/therapeutic use , Arachidonic Acids/therapeutic use , Benzoates/therapeutic use , Obesity/drug therapy , Phenylurea Compounds/therapeutic use , Adipogenesis , Adipose Tissue, Brown/cytology , Adipose Tissue, Brown/drug effects , Adipose Tissue, Brown/metabolism , Animals , Anti-Obesity Agents/administration & dosage , Anti-Obesity Agents/pharmacology , Arachidonic Acids/administration & dosage , Arachidonic Acids/pharmacology , Benzoates/administration & dosage , Benzoates/pharmacology , Blood Glucose/metabolism , Carnitine O-Palmitoyltransferase/metabolism , Diet, High-Fat , Epoxide Hydrolases/antagonists & inhibitors , Fatty Acids/metabolism , Male , Mice , Mice, Inbred C57BL , NF-kappa B/metabolism , Obesity/etiology , Obesity/metabolism , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/metabolism , Phenylurea Compounds/administration & dosage , Phenylurea Compounds/pharmacology
11.
Viruses ; 13(1)2021 Jan 11.
Article in English | MEDLINE | ID: covidwho-1022024

ABSTRACT

Enteric symptomology seen in early-stage severe acute respiratory syndrome (SARS)-2003 and COVID-19 is evidence of virus replication occurring in the intestine, liver and pancreas. Aberrant lipid metabolism in morbidly obese individuals adversely affects the COVID-19 immune response and increases disease severity. Such observations are in line with the importance of lipid metabolism in COVID-19, and point to the gut as a site for intervention as well as a therapeutic target in treating the disease. Formation of complex lipid membranes and palmitoylation of coronavirus proteins are essential during viral replication and assembly. Inhibition of fatty acid synthase (FASN) and restoration of lipid catabolism by activation of AMP-activated protein kinase (AMPK) impede replication of coronaviruses closely related to SARS-coronavirus-2 (CoV-2). In vitro findings and clinical data reveal that the FASN inhibitor, orlistat, and the AMPK activator, metformin, may inhibit coronavirus replication and reduce systemic inflammation to restore immune homeostasis. Such observations, along with the known mechanisms of action for these types of drugs, suggest that targeting fatty acid lipid metabolism could directly inhibit virus replication while positively impacting the patient's response to COVID-19.


Subject(s)
COVID-19/metabolism , Fatty Acids/metabolism , Lipid Metabolism , SARS-CoV-2/physiology , AMP-Activated Protein Kinases/metabolism , AMP-Activated Protein Kinases/pharmacology , Antiviral Agents/pharmacology , Antiviral Agents/therapeutic use , COVID-19/drug therapy , COVID-19/virology , Digestive System/drug effects , Digestive System/virology , Fatty Acid Synthases/antagonists & inhibitors , Fatty Acid Synthases/metabolism , Humans , Metformin/therapeutic use , Obesity/drug therapy , Obesity/metabolism , Obesity/virology , Orlistat/therapeutic use , SARS-CoV-2/drug effects , Viral Proteins/metabolism , Virus Assembly/drug effects , Virus Replication/drug effects
12.
Expert Opin Drug Discov ; 15(2): 159-177, 2020 02.
Article in English | MEDLINE | ID: covidwho-825219

ABSTRACT

Introduction: S-acylation is the attachment of fatty acids not only to cysteines of cellular, but also of viral proteins. The modification is often crucial for the protein´s function and hence for virus replication. Transfer of fatty acids is mediated by one or several of the 23 members of the ZDHHC family of proteins. Since their genes are linked to various human diseases, they represent drug targets.Areas covered: The authors explore whether targeting acylation of viral proteins might be a strategy to combat viral diseases. Many human pathogens contain S-acylated proteins; the ZDHHCs involved in their acylation are currently identified. Based on the 3D structure of two ZDHHCs, the regulation and the biochemistry of the palmitolyation reaction and the lipid and protein substrate specificities are discussed. The authors then speculate how ZDHHCs might recognize S-acylated membrane proteins of Influenza virus.Expert opinion: Although many viral diseases can now be treated, the available drugs bind to viral proteins that rapidly mutate and become resistant. To develop inhibitors for the genetically more stable cellular ZDHHCs, their binding sites for viral substrates need to be identified. If only a few cellular proteins are recognized by the same binding site, development of specific inhibitors may have therapeutic potential.


Subject(s)
Acyltransferases/metabolism , Antiviral Agents/pharmacology , Virus Diseases/drug therapy , Acylation/physiology , Animals , Binding Sites , Drug Development , Fatty Acids/metabolism , Humans , Lipoylation/physiology , Viral Proteins/metabolism , Virus Diseases/enzymology , Virus Diseases/virology
13.
JCI Insight ; 5(14)2020 07 23.
Article in English | MEDLINE | ID: covidwho-607189

ABSTRACT

BACKGROUNDReprogramming of host metabolism supports viral pathogenesis by fueling viral proliferation, by providing, for example, free amino acids and fatty acids as building blocks.METHODSTo investigate metabolic effects of SARS-CoV-2 infection, we evaluated serum metabolites of patients with COVID-19 (n = 33; diagnosed by nucleic acid testing), as compared with COVID-19-negative controls (n = 16).RESULTSTargeted and untargeted metabolomics analyses identified altered tryptophan metabolism into the kynurenine pathway, which regulates inflammation and immunity. Indeed, these changes in tryptophan metabolism correlated with interleukin-6 (IL-6) levels. Widespread dysregulation of nitrogen metabolism was also seen in infected patients, with altered levels of most amino acids, along with increased markers of oxidant stress (e.g., methionine sulfoxide, cystine), proteolysis, and renal dysfunction (e.g., creatine, creatinine, polyamines). Increased circulating levels of glucose and free fatty acids were also observed, consistent with altered carbon homeostasis. Interestingly, metabolite levels in these pathways correlated with clinical laboratory markers of inflammation (i.e., IL-6 and C-reactive protein) and renal function (i.e., blood urea nitrogen).CONCLUSIONIn conclusion, this initial observational study identified amino acid and fatty acid metabolism as correlates of COVID-19, providing mechanistic insights, potential markers of clinical severity, and potential therapeutic targets.FUNDINGBoettcher Foundation Webb-Waring Biomedical Research Award; National Institute of General and Medical Sciences, NIH; and National Heart, Lung, and Blood Institute, NIH.


Subject(s)
Coronavirus Infections/metabolism , Fatty Acids/metabolism , Interleukin-6/metabolism , Kynurenine/metabolism , Oxidative Stress , Pneumonia, Viral/metabolism , Renal Insufficiency/metabolism , Adult , Aged , Amino Acids/metabolism , Betacoronavirus , Blood Glucose/metabolism , COVID-19 , Case-Control Studies , Creatine/metabolism , Creatinine/metabolism , Cystine , Fatty Acids, Nonesterified/metabolism , Female , Humans , Male , Metabolome , Metabolomics , Methionine/analogs & derivatives , Middle Aged , Pandemics , Polyamines/metabolism , Proteolysis , SARS-CoV-2 , Tryptophan/metabolism
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