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Han S, Moon S, Chung YW, Ryu JH. NADPH Oxidase 4-mediated Alveolar Macrophage Recruitment to Lung Attenuates Neutrophilic Inflammation in Staphylococcus aureus Infection. Immune Netw 2023; 23:e42. [PMID: 37970233 PMCID: PMC10643333 DOI: 10.4110/in.2023.23.e42] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 09/25/2023] [Accepted: 10/22/2023] [Indexed: 11/17/2023] Open
Abstract
When the lungs are infected with bacteria, alveolar macrophages (AMs) are recruited to the site and play a crucial role in protecting the host by reducing excessive lung inflammation. However, the regulatory mechanisms that trigger the recruitment of AMs to lung alveoli during an infection are still not fully understood. In this study, we identified a critical role for NADPH oxidase 4 (NOX4) in the recruitment of AMs during Staphylococcus aureus lung infection. We found that NOX4 knockout (KO) mice showed decreased recruitment of AMs and increased lung neutrophils and injury in response to S. aureus infection compared to wild-type (WT) mice. Interestingly, the burden of S. aureus in the lungs was not different between NOX4 KO and WT mice. Furthermore, we observed that depletion of AMs in WT mice during S. aureus infection increased the number of neutrophils and lung injury to a similar level as that observed in NOX4 KO mice. Additionally, we found that expression of intercellular adhesion molecule-1 (ICAM1) in NOX4 KO mice-derived lung endothelial cells was lower than that in WT mice-derived endothelial cells. Therefore, we conclude that NOX4 plays a crucial role in inducing the recruitment of AMs by controlling ICAM1 expression in lung endothelial cells, which is responsible for resolving lung inflammation during acute S. aureus infection.
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Affiliation(s)
- Seunghan Han
- Department of Biomedical Sciences, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Sungmin Moon
- Department of Biomedical Sciences, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Youn Wook Chung
- Department of Biomedical Sciences, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Ji-Hwan Ryu
- Department of Biomedical Sciences, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul 03722, Korea
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2
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Tu GW, Zhang Y, Ma JF, Hou JY, Hao GW, Su Y, Luo JC, Sheng L, Luo Z. Extracellular vesicles derived from CD4 + T cells carry DGKK to promote sepsis-induced lung injury by regulating oxidative stress and inflammation. Cell Mol Biol Lett 2023; 28:24. [PMID: 36959535 PMCID: PMC10035494 DOI: 10.1186/s11658-023-00435-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 02/28/2023] [Indexed: 03/25/2023] Open
Abstract
BACKGROUND Sepsis is an abnormal immune response after infection, wherein the lung is the most susceptible organ to fail, leading to acute lung injury. To overcome the limitations of current therapeutic strategies and develop more specific treatment, the inflammatory process, in which T cell-derived extracellular vesicles (EVs) play a central role, should be explored deeply. METHODS Liquid chromatography-tandem mass spectrometry was performed for serum EV protein profiling. The serum diacylglycerol kinase kappa (DGKK) and endotoxin contents of patients with sepsis-induced lung injury were measured. Apoptosis, oxidative stress, and inflammation in A549 cells, bronchoalveolar lavage fluid, and lung tissues of mice were measured by flow cytometry, biochemical analysis, enzyme-linked immunosorbent assay, quantitative real-time polymerase chain reaction, and western blot. RESULTS DGKK, the key regulator of the diacylglycerol (DAG)/protein kinase C (PKC) pathway, exhibited elevated expression in serum EVs of patients with sepsis-induced lung injury and showed strong correlation with sepsis severity and disease progression. DGKK was expressed in CD4+ T cells under regulation of the NF-κB pathway and delivered by EVs to target cells, including alveolar epithelial cells. EVs produced by CD4+ T lymphocytes exerted toxic effects on A549 cells to induce apoptotic cell death, oxidative cell damage, and inflammation. In mice with sepsis induced by cecal ligation and puncture, EVs derived from CD4+ T cells also promoted tissue damage, oxidative stress, and inflammation in the lungs. These toxic effects of T cell-derived EVs were attenuated by the inhibition of PKC and NOX4, the downstream effectors of DGKK and DAG. CONCLUSIONS This approach established the mechanism that T-cell-derived EVs carrying DGKK triggered alveolar epithelial cell apoptosis, oxidative stress, inflammation, and tissue damage in sepsis-induced lung injury through the DAG/PKC/NOX4 pathway. Thus, T-cell-derived EVs and the elevated distribution of DGKK should be further investigated to develop therapeutic strategies for sepsis-induced lung injury.
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Affiliation(s)
- Guo-Wei Tu
- Cardiac Intensive Care Center, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yi Zhang
- Biomedical Research Center, Institute for Clinical Sciences, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jie-Fei Ma
- Department of Critical Care Medicine, Zhongshan Hospital (Xiamen), Fudan University, Xiamen, China
| | - Jun-Yi Hou
- Cardiac Intensive Care Center, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Guang-Wei Hao
- Cardiac Intensive Care Center, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Ying Su
- Cardiac Intensive Care Center, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jing-Chao Luo
- Cardiac Intensive Care Center, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Lulu Sheng
- Department of Emergency Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China.
| | - Zhe Luo
- Cardiac Intensive Care Center, Zhongshan Hospital, Fudan University, Shanghai, China.
- Department of Critical Care Medicine, Zhongshan Hospital (Xiamen), Fudan University, Xiamen, China.
- Shanghai Key Laboratory of Lung Inflammation and Injury, Shanghai, China.
- Department of Critical Care Medicine, Shanghai Xuhui Central Hospital, Zhongshan-Xuhui Hospital, Fudan University, Shanghai, China.
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3
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Smith CD, Maines LW, Keller SN, Katz Ben-Yair V, Fathi R, Plasse TF, Levitt ML. Recent Progress in the Development of Opaganib for the Treatment of Covid-19. Drug Des Devel Ther 2022; 16:2199-2211. [PMID: 35855741 PMCID: PMC9288228 DOI: 10.2147/dddt.s367612] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 07/02/2022] [Indexed: 12/15/2022] Open
Abstract
The Covid-19 pandemic driven by the SARS-CoV-2 virus continues to exert extensive humanitarian and economic stress across the world. Although antivirals active against mild disease have been identified recently, new drugs to treat moderate and severe Covid-19 patients are needed. Sphingolipids regulate key pathologic processes, including viral proliferation and pathologic host inflammation. Opaganib (aka ABC294640) is a first-in-class clinical drug targeting sphingolipid metabolism for the treatment of cancer and inflammatory diseases. Recent work demonstrates that opaganib also has antiviral activity against several viruses including SARS-CoV-2. A recently completed multinational Phase 2/3 clinical trial of opaganib in patients hospitalized with Covid-19 demonstrated that opaganib can be safely administered to these patients, and more importantly, resulted in a 62% decrease in mortality in a large subpopulation of patients with moderately severe Covid-19. Furthermore, acceleration of the clearance of the virus was observed in opaganib-treated patients. Understanding the biochemical mechanism for the anti-SARS-CoV-2 activity of opaganib is essential for optimizing Covid-19 treatment protocols. Opaganib inhibits three key enzymes in sphingolipid metabolism: sphingosine kinase-2 (SK2); dihydroceramide desaturase (DES1); and glucosylceramide synthase (GCS). Herein, we describe a tripartite model by which opaganib suppresses infection and replication of SARS-CoV-2 by inhibiting SK2, DES1 and GCS. The potential impact of modulation of sphingolipid signaling on multi-organ dysfunction in Covid-19 patients is also discussed.
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Affiliation(s)
- Charles D Smith
- Apogee Biotechnology Corporation, Hummelstown, PA, USA
- Correspondence: Charles D Smith, Apogee Biotechnology Corporation, 1214 Research Blvd, Suite 2015, Hummelstown, PA, 17036, USA, Tel +1 843 814 9257, Email
| | - Lynn W Maines
- Apogee Biotechnology Corporation, Hummelstown, PA, USA
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Harijith A, Basa P, Ha A, Thomas J, Jafri A, Fu P, MacFarlane PM, Raffay TM, Natarajan V, Sudhadevi T. NOX4 Mediates Epithelial Cell Death in Hyperoxic Acute Lung Injury Through Mitochondrial Reactive Oxygen Species. Front Pharmacol 2022; 13:880878. [PMID: 35662702 PMCID: PMC9160661 DOI: 10.3389/fphar.2022.880878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 04/18/2022] [Indexed: 11/13/2022] Open
Abstract
Management of acute respiratory distress involves O2 supplementation, which is lifesaving, but causes severe hyperoxic acute lung injury (HALI). NADPH oxidase (NOX) could be a major source of reactive oxygen species (ROS) in hyperoxia (HO). Epithelial cell death is a crucial step in the development of many lung diseases. Alveolar type II (AT2) cells are the metabolically active epithelial cells of alveoli that serve as a source of AT1 cells following lung injury. The aim of this study was to determine the possible role of AT2 epithelial cell NOX4 in epithelial cell death from HALI. Wild type (WT), Nox4 fl/fl (control), and Nox4 -/- Spc-Cre mice were exposed to room air (NO) or 95% O2 (HO) to investigate the structural and functional changes in the lung. C57BL/6J WT animals subjected to HO showed increased expression of lung NOX4 compared to NO. Significant HALI, increased bronchoalveolar lavage cell counts, increased protein levels, elevated proinflammatory cytokines and increased AT2 cell death seen in hyperoxic Nox4 fl/fl control mice were attenuated in HO-exposed Nox4 -/- Spc-Cre mice. HO-induced expression of NOX4 in MLE cells resulted in increased mitochondrial (mt) superoxide production and cell apoptosis, which was reduced in NOX4 siRNA silenced cells. This study demonstrates a novel role for epithelial cell NOX4 in accelerating lung epithelial cell apoptosis from HALI. Deletion of the Nox4 gene in AT2 cells or silencing NOX4 in lung epithelial cells protected the lungs from severe HALI with reduced apoptosis and decreased mt ROS production in HO. These results suggest NOX4 as a potential target for the treatment of HALI.
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Affiliation(s)
- Anantha Harijith
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Prathima Basa
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Alison Ha
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Jaya Thomas
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Anjum Jafri
- Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Panfeng Fu
- Department of Pharmacology and Regenerative Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Peter M. MacFarlane
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Thomas M. Raffay
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Viswanathan Natarajan
- Department of Pharmacology and Regenerative Medicine, University of Illinois at Chicago, Chicago, IL, United States
- Department of Internal Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Tara Sudhadevi
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
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5
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Non-Coding RNAs and Reactive Oxygen Species–Symmetric Players of the Pathogenesis Associated with Bacterial and Viral Infections. Symmetry (Basel) 2021. [DOI: 10.3390/sym13071307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Infections can be triggered by a wide range of pathogens. However, there are few strains of bacteria that cause illness, but some are quite life-threatening. Likewise, viral infections are responsible for many human diseases, usually characterized by high contagiousness. Hence, as bacterial and viral infections can both cause similar symptoms, it can be difficult to determine the exact cause of a specific infection, and this limitation is critical. However, recent scientific advances have geared us up with the proper tools required for better diagnoses. Recent discoveries have confirmed the involvement of non-coding RNAs (ncRNAs) in regulating the pathogenesis of certain bacterial or viral infections. Moreover, the presence of reactive oxygen species (ROS) is also known as a common infection trait that can be used to achieve a more complete description of such pathogen-driven conditions. Thus, this opens further research opportunities, allowing scientists to explore infection-associated genetic patterns and develop better diagnosis and treatment methods. Therefore, the aim of this review is to summarize the current knowledge of the implication of ncRNAs and ROS in bacterial and viral infections, with great emphasis on their symmetry but, also, on their main differences.
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6
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Brindley DN. Viswanathan Natarajan: A Giant in Lipid Research and Pulmonary Disease and a True Gentleman. Cell Biochem Biophys 2021; 79:429-432. [PMID: 34251599 PMCID: PMC8274259 DOI: 10.1007/s12013-021-01018-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/22/2021] [Indexed: 11/04/2022]
Abstract
This article is intended to recognize and the life time contribution that Dr. Viswanathan Natarajan has made to the advancement of lipid metabolism and lipid signaling. In particular, his major contributions in the last three decades have been made in understanding how lipids such as phosphatidic acid, lysophosphatidic acid, sphingosine 1-phosphate and cardiolipin contribute to healthy lung functions and to a variety of lung pathologies. We celebrate a truly remarkable career and look forward to seeing even more remarkable discoveries.
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Affiliation(s)
- David N Brindley
- Department of Biochemistry, Cancer Research Institute of Northern Alberta, 357 Heritage Medical Research Centre, University of Alberta, Edmonton, T6G 2S2, AB, Canada.
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Nijmeh J, Levy BD. Lipid-Derived Mediators are Pivotal to Leukocyte and Lung Cell Responses in Sepsis and ARDS. Cell Biochem Biophys 2021; 79:449-459. [PMID: 34176102 PMCID: PMC8236093 DOI: 10.1007/s12013-021-01012-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 06/04/2021] [Indexed: 12/14/2022]
Abstract
Acute inflammation in the lung is essential for host defense against pathogens and other injuries but chronic or excessive inflammation can contribute to several common respiratory diseases. In health, the inflammatory response is controlled by several cellular and molecular mechanisms. In addition to anti-inflammatory processes, there are non-phlogistic pro-resolving mechanisms that are engaged to promote the resolution of inflammation and a return to homeostasis. Defects in the production or actions of specialized pro-resolving mediators are associated with diseases characterized by excess or chronic inflammation. In this article, we review cellular and biochemical mechanisms for specialized pro-resolving mediators in health and in sepsis and the acute respiratory distress syndrome as examples of unrestrained inflammatory responses that result in life-threatening pathology. We are honored to contribute to this special edition of the Journal to help celebrate Professor Viswanathan Natarajan’s contributions to our understanding of lipid-derived mediators and metabolism in lung cell responses to inflammatory, infectious, or mechanical insults; his foundational discoveries in cell biochemistry and biophysics are continuing to catalyze further advances by the field to uncover the mechanistic underpinnings of important human diseases.
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Affiliation(s)
- Julie Nijmeh
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Bruce D Levy
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
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8
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Dumas A, Knaus UG. Raising the 'Good' Oxidants for Immune Protection. Front Immunol 2021; 12:698042. [PMID: 34149739 PMCID: PMC8213335 DOI: 10.3389/fimmu.2021.698042] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 05/18/2021] [Indexed: 12/12/2022] Open
Abstract
Redox medicine is a new therapeutic concept targeting reactive oxygen species (ROS) and secondary reaction products for health benefit. The concomitant function of ROS as intracellular second messengers and extracellular mediators governing physiological redox signaling, and as damaging radicals instigating or perpetuating various pathophysiological conditions will require selective strategies for therapeutic intervention. In addition, the reactivity and quantity of the oxidant species generated, its source and cellular location in a defined disease context need to be considered to achieve the desired outcome. In inflammatory diseases associated with oxidative damage and tissue injury, ROS source specific inhibitors may provide more benefit than generalized removal of ROS. Contemporary approaches in immunity will also include the preservation or even elevation of certain oxygen metabolites to restore or improve ROS driven physiological functions including more effective redox signaling and cell-microenvironment communication, and to induce mucosal barrier integrity, eubiosis and repair processes. Increasing oxidants by host-directed immunomodulation or by exogenous supplementation seems especially promising for improving host defense. Here, we summarize examples of beneficial ROS in immune homeostasis, infection, and acute inflammatory disease, and address emerging therapeutic strategies for ROS augmentation to induce and strengthen protective host immunity.
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Affiliation(s)
- Alexia Dumas
- Conway Institute, School of Medicine, University College Dublin, Dublin, Ireland
| | - Ulla G Knaus
- Conway Institute, School of Medicine, University College Dublin, Dublin, Ireland
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Ebenezer DL, Ramchandran R, Fu P, Mangio LA, Suryadevara V, Ha AW, Berdyshev E, Van Veldhoven PP, Kron SJ, Schumacher F, Kleuser B, Natarajan V. Nuclear Sphingosine-1-phosphate Lyase Generated ∆2-hexadecenal is A Regulator of HDAC Activity and Chromatin Remodeling in Lung Epithelial Cells. Cell Biochem Biophys 2021; 79:575-592. [PMID: 34085165 DOI: 10.1007/s12013-021-01005-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2021] [Indexed: 12/14/2022]
Abstract
Sphingosine-1-phosphate (S1P), a bioactive lipid mediator, is generated from sphingosine by sphingosine kinases (SPHKs) 1 and 2 and is metabolized to ∆2-hexadecenal (∆2-HDE) and ethanolamine phosphate by S1P lyase (S1PL) in mammalian cells. We have recently demonstrated the activation of nuclear SPHK2 and the generation of S1P in the nucleus of lung epithelial cells exposed to Pseudomonas aeruginosa. Here, we have investigated the nuclear localization of S1PL and the role of ∆2-HDE generated from S1P in the nucleus as a modulator of histone deacetylase (HDAC) activity and histone acetylation. Electron micrographs of the nuclear fractions isolated from MLE-12 cells showed nuclei free of ER contamination, and S1PL activity was detected in nuclear fractions isolated from primary lung bronchial epithelial cells and alveolar epithelial MLE-12 cells. Pseudomonas aeruginosa-mediated nuclear ∆2-HDE generation, and H3/H4 histone acetylation was attenuated by S1PL inhibitors in MLE-12 cells and human bronchial epithelial cells. In vitro, the addition of exogenous ∆2-HDE (100-10,000 nM) to lung epithelial cell nuclear preparations inhibited HDAC1/2 activity, and increased acetylation of Histone H3 and H4, whereas similar concentrations of S1P did not show a significant change. In addition, incubation of ∆2-HDE with rHDAC1 generated five different amino acid adducts as detected by LC-MS/MS; the predominant adduct being ∆2-HDE with lysine residues of HDAC1. Together, these data show an important role for the nuclear S1PL-derived ∆2-HDE in the modification of HDAC activity, histone acetylation, and chromatin remodeling in lung epithelial cells.
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Affiliation(s)
- David L Ebenezer
- Departments of Pharmacology & Regenerative Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Ramaswamy Ramchandran
- Departments of Pharmacology & Regenerative Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Panfeng Fu
- The Affiliated Hospital of School of Medicine, Ningbo University, Ningbo, China
| | - Lizar A Mangio
- Departments of Pharmacology & Regenerative Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Vidyani Suryadevara
- Departments of Pharmacology & Regenerative Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Alison W Ha
- Department of Biochemistry & Molecular Genetics, University of Illinois at Chicago, Chicago, IL, USA
| | - Evgeny Berdyshev
- Department of Medicine, National Jewish Medical Center, Denver, CO, USA
| | - Paul P Van Veldhoven
- LIPIT, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Stephen J Kron
- Department of Molecular Genetics and Cell Biology and Ludwig Center for Metastasis Research, The University of Chicago, Chicago, IL, USA
| | - Fabian Schumacher
- Institute of Pharmacy, Department of Pharmacology & Toxicology, Freie Universität Berlin, Berlin, Germany
| | - Burkhard Kleuser
- Institute of Pharmacy, Department of Pharmacology & Toxicology, Freie Universität Berlin, Berlin, Germany
| | - Viswanathan Natarajan
- Departments of Pharmacology & Regenerative Medicine, University of Illinois at Chicago, Chicago, IL, USA. .,Department of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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Diaz Escarcega R, McCullough LD, Tsvetkov AS. The Functional Role of Sphingosine Kinase 2. Front Mol Biosci 2021; 8:683767. [PMID: 34055895 PMCID: PMC8160245 DOI: 10.3389/fmolb.2021.683767] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 04/30/2021] [Indexed: 12/19/2022] Open
Abstract
Sphingosine-1-phosphate (S1P) is a bioactive lipid molecule that is present in all eukaryotic cells and plays key roles in various extracellular, cytosolic, and nuclear signaling pathways. Two sphingosine kinase isoforms, sphingosine kinase 1 (SPHK1) and sphingosine kinase 2 (SPHK2), synthesize S1P by phosphorylating sphingosine. While SPHK1 is a cytoplasmic kinase, SPHK2 is localized to the nucleus, endoplasmic reticulum, and mitochondria. The SPHK2/S1P pathway regulates transcription, telomere maintenance, mitochondrial respiration, among many other processes. SPHK2 is under investigation as a target for treating many age-associated conditions, such as cancer, stroke, and neurodegeneration. In this review, we will focus on the role of SPHK2 in health and disease.
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Affiliation(s)
- Rocio Diaz Escarcega
- Department of Neurology, The University of Texas McGovern Medical School at Houston, Houston, TX, United States
| | - Louise D McCullough
- Department of Neurology, The University of Texas McGovern Medical School at Houston, Houston, TX, United States.,The University of Texas Graduate School of Biomedical Sciences, Houston, TX, United States
| | - Andrey S Tsvetkov
- Department of Neurology, The University of Texas McGovern Medical School at Houston, Houston, TX, United States.,The University of Texas Graduate School of Biomedical Sciences, Houston, TX, United States.,UTHealth Consortium on Aging, The University of Texas McGovern Medical School, Houston, TX, United States
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Abstract
An overview of Prof. Viswanathan Natarajan's journey in academia as a mentor, teacher, and lipid scientist for nearly 50 years is presented. As a graduate student, Dr. Natarajan interrogated biosynthesis and catabolism of phospholipids in the developing brain; however, in the last five decades, he has been investigating the role of sphingolipids and sphingolipid-metabolizing enzymes in pulmonary endothelial cells, epithelial cells, and fibroblasts under normal conditions and during various lung pathologies such as sepsis, asthma, pulmonary hypertension, idiopathic pulmonary fibrosis, bronchopulmonary dysplasia, and lung cancer. His recent work on sphingosine-1-phosphate and lysophosphatidic acid metabolism in pre-clinical animal models has identified small molecule inhibitors in the signaling pathways that could have therapeutic potential in ameliorating pulmonary fibrosis, hypoxia-induced pulmonary hypertension, lung cancer, and bronchopulmonary dysplasia. Future research in bioactive lipids in combination with OMICS should unravel the importance of various lipid mediators as modulators of cell function under normal and pathological conditions.
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Affiliation(s)
- Viswanathan Natarajan
- Departments of Pharmacology & Regenerative Medicine and Medicine, University of Illinois, Chicago, IL 60612 USA
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