1
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Tang Y, Majewska M, Leß B, Mehmeti I, Wollnitzke P, Semleit N, Levkau B, Saba JD, van Echten-Deckert G, Gurgul-Convey E. The fate of intracellular S1P regulates lipid droplet turnover and lipotoxicity in pancreatic beta-cells. J Lipid Res 2024; 65:100587. [PMID: 38950680 DOI: 10.1016/j.jlr.2024.100587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 06/07/2024] [Accepted: 06/22/2024] [Indexed: 07/03/2024] Open
Abstract
Lipotoxicity has been considered the main cause of pancreatic beta-cell failure during type 2 diabetes development. Lipid droplets (LD) are believed to regulate the beta-cell sensitivity to free fatty acids (FFA), but the underlying molecular mechanisms are largely unclear. Accumulating evidence points, however, to an important role of intracellular sphingosine-1-phosphate (S1P) metabolism in lipotoxicity-mediated disturbances of beta-cell function. In the present study, we compared the effects of an increased irreversible S1P degradation (S1P-lyase, SPL overexpression) with those associated with an enhanced S1P recycling (overexpression of S1P phosphatase 1, SGPP1) on LD formation and lipotoxicity in rat INS1E beta-cells. Interestingly, although both approaches led to a reduced S1P concentration, they had opposite effects on the susceptibility to FFA. Overexpression of SGPP1 prevented FFA-mediated caspase-3 activation by a mechanism involving an enhanced lipid storage capacity and prevention of oxidative stress. In contrast, SPL overexpression limited LD biogenesis, content, and size, while accelerating lipophagy. This was associated with FFA-induced hydrogen peroxide formation, mitochondrial fragmentation, and dysfunction, as well as ER stress. These changes coincided with the upregulation of proapoptotic ceramides but were independent of lipid peroxidation rate. Also in human EndoC-βH1 beta-cells, suppression of SPL with simultaneous overexpression of SGPP1 led to a similar and even more pronounced LD phenotype as that in INS1E-SGPP1 cells. Thus, intracellular S1P turnover significantly regulates LD content and size and influences beta-cell sensitivity to FFA.
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Affiliation(s)
- Yadi Tang
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Mariola Majewska
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Britta Leß
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Ilir Mehmeti
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Philipp Wollnitzke
- Institute of Molecular Medicine III, University Hospital Düsseldorf and Heinrich Heine University, Düsseldorf, Germany
| | - Nina Semleit
- Institute of Molecular Medicine III, University Hospital Düsseldorf and Heinrich Heine University, Düsseldorf, Germany
| | - Bodo Levkau
- Institute of Molecular Medicine III, University Hospital Düsseldorf and Heinrich Heine University, Düsseldorf, Germany
| | - Julie D Saba
- Division of Hematology/Oncology, Department of Pediatrics, University of California. San Francisco, Oakland, CA, USA
| | | | - Ewa Gurgul-Convey
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany.
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2
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Xiao J. Sphingosine 1-Phosphate Lyase in the Developing and Injured Nervous System: a Dichotomy? Mol Neurobiol 2023; 60:6869-6882. [PMID: 37507574 PMCID: PMC10657793 DOI: 10.1007/s12035-023-03524-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023]
Abstract
Sphingosine 1-phosphate lyase (SPL) is the terminal enzyme that controls the degradation of the bioactive lipid sphingosine 1-phosphate (S1P) within an interconnected sphingolipid metabolic network. The unique metabolic position of SPL in maintaining S1P levels implies SPL could be an emerging new therapeutic target. Over the past decade, an evolving effort has been made to unravel the role of SPL in the nervous system; however, to what extent SPL influences the developing and mature nervous system through altering S1P biosynthesis remains opaque. While congenital SPL deletion is associated with deficits in the developing nervous system, the loss of SPL activity in adults appears to be neuroprotective in acquired neurological disorders. The controversial findings concerning SPL's role in the nervous system are further constrained by the current genetic and pharmacological tools. This review attempts to focus on the multi-faceted nature of SPL function in the mammalian nervous systems, implying its dichotomy in the developing and adult central nervous system (CNS). This article also highlights SPL is emerging as a therapeutic molecule that can be selectively targeted to modulate S1P for the treatment of acquired neurodegenerative diseases, raising new questions for future investigation. The development of cell-specific inducible conditional SPL mutants and selective pharmacological tools will allow the precise understanding of SPL's function in the adult CNS, which will aid the development of a new strategy focusing on S1P-based therapies for neuroprotection.
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Affiliation(s)
- Junhua Xiao
- Department of Health Sciences and Biostatistics, School of Health Sciences, Swinburne University of Technology, John Street, Hawthorn, VIC, 3022, Australia.
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3
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Pierucci F, Chirco A, Meacci E. Irisin Is Target of Sphingosine-1-Phosphate/Sphingosine-1-Phosphate Receptor-Mediated Signaling in Skeletal Muscle Cells. Int J Mol Sci 2023; 24:10548. [PMID: 37445724 DOI: 10.3390/ijms241310548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 06/17/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023] Open
Abstract
Irisin is a hormone-like myokine produced in abundance by skeletal muscle (SkM) in response to exercise. This myokine, identical in humans and mice, is involved in many signaling pathways related to metabolic processes. Despite much evidence on the regulators of irisin and the relevance of sphingolipids for SkM cell biology, the contribution of these latter bioactive lipids to the modulation of the myokine in SkM is missing. In particular, we have examined the potential involvement in irisin formation/release of sphingosine-1-phosphate (S1P), an interesting bioactive molecule able to act as an intracellular lipid mediator as well as a ligand of specific G-protein-coupled receptors (S1PR). We demonstrate the existence of distinct intracellular pools of S1P able to affect the expression of the irisin precursor FNDC. In addition, we establish the crucial role of the S1P/S1PR axis in irisin formation/release as well as the autocrine/paracrine effects of irisin on myoblast proliferation and myogenic differentiation. Altogether, these findings provide the first evidence for a functional crosstalk between the S1P/S1PR axis and irisin signaling, which may open new windows for potential therapeutic treatment of SkM dysfunctions.
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Affiliation(s)
- Federica Pierucci
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, 50134 Firenze, Italy
| | - Antony Chirco
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, 50134 Firenze, Italy
| | - Elisabetta Meacci
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, 50134 Firenze, Italy
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4
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Harlé G, Kowalski C, Dubrot J, Brighouse D, Clavel G, Pick R, Bessis N, Niven J, Scheiermann C, Gannagé M, Hugues S. Macroautophagy in lymphatic endothelial cells inhibits T cell-mediated autoimmunity. J Exp Med 2021; 218:212000. [PMID: 33861848 PMCID: PMC8056750 DOI: 10.1084/jem.20201776] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 12/21/2020] [Accepted: 02/05/2021] [Indexed: 12/11/2022] Open
Abstract
Lymphatic endothelial cells (LECs) present peripheral tissue antigens to induce T cell tolerance. In addition, LECs are the main source of sphingosine-1-phosphate (S1P), promoting naive T cell survival and effector T cell exit from lymph nodes (LNs). Autophagy is a physiological process essential for cellular homeostasis. We investigated whether autophagy in LECs modulates T cell activation in experimental arthritis. Whereas genetic abrogation of autophagy in LECs does not alter immune homeostasis, it induces alterations of the regulatory T cell (T reg cell) population in LNs from arthritic mice, which might be linked to MHCII-mediated antigen presentation by LECs. Furthermore, inflammation-induced autophagy in LECs promotes the degradation of Sphingosine kinase 1 (SphK1), resulting in decreased S1P production. Consequently, in arthritic mice lacking autophagy in LECs, pathogenic Th17 cell migration toward LEC-derived S1P gradients and egress from LNs are enhanced, as well as infiltration of inflamed joints, resulting in exacerbated arthritis. Our results highlight the autophagy pathway as an important regulator of LEC immunomodulatory functions in inflammatory conditions.
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Affiliation(s)
- Guillaume Harlé
- Department of Pathology and Immunology, School of Medicine, University of Geneva, Geneva, Switzerland
| | - Camille Kowalski
- Department of Pathology and Immunology, School of Medicine, University of Geneva, Geneva, Switzerland
| | - Juan Dubrot
- Department of Pathology and Immunology, School of Medicine, University of Geneva, Geneva, Switzerland
| | - Dale Brighouse
- Department of Pathology and Immunology, School of Medicine, University of Geneva, Geneva, Switzerland
| | - Gaëlle Clavel
- Institut National de la Santé et de la Recherche Médicale, UMR 1125, Université Sorbonne Paris Cité, Université Paris, Paris, France
| | - Robert Pick
- Department of Pathology and Immunology, School of Medicine, University of Geneva, Geneva, Switzerland
| | - Natacha Bessis
- Service of Immunology and Allergy, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Jennifer Niven
- Department of Pathology and Immunology, School of Medicine, University of Geneva, Geneva, Switzerland
| | - Christoph Scheiermann
- Department of Pathology and Immunology, School of Medicine, University of Geneva, Geneva, Switzerland
| | - Monique Gannagé
- Service of Immunology and Allergy, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Stéphanie Hugues
- Department of Pathology and Immunology, School of Medicine, University of Geneva, Geneva, Switzerland
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5
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Arsenault EJ, McGill CM, Barth BM. Sphingolipids as Regulators of Neuro-Inflammation and NADPH Oxidase 2. Neuromolecular Med 2021; 23:25-46. [PMID: 33547562 PMCID: PMC9020407 DOI: 10.1007/s12017-021-08646-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 01/14/2021] [Indexed: 12/14/2022]
Abstract
Neuro-inflammation accompanies numerous neurological disorders and conditions where it can be associated with a progressive neurodegenerative pathology. In a similar manner, alterations in sphingolipid metabolism often accompany or are causative features in degenerative neurological conditions. These include dementias, motor disorders, autoimmune conditions, inherited metabolic disorders, viral infection, traumatic brain and spinal cord injury, psychiatric conditions, and more. Sphingolipids are major regulators of cellular fate and function in addition to being important structural components of membranes. Their metabolism and signaling pathways can also be regulated by inflammatory mediators. Therefore, as certain sphingolipids exert distinct and opposing cellular roles, alterations in their metabolism can have major consequences. Recently, regulation of bioactive sphingolipids by neuro-inflammatory mediators has been shown to activate a neuronal NADPH oxidase 2 (NOX2) that can provoke damaging oxidation. Therefore, the sphingolipid-regulated neuronal NOX2 serves as a mechanistic link between neuro-inflammation and neurodegeneration. Moreover, therapeutics directed at sphingolipid metabolism or the sphingolipid-regulated NOX2 have the potential to alleviate neurodegeneration arising out of neuro-inflammation.
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Affiliation(s)
- Emma J Arsenault
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH, 03824, USA
| | - Colin M McGill
- Department of Chemistry, University of Alaska Anchorage, Anchorage, AK, 99508, USA
| | - Brian M Barth
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH, 03824, USA.
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6
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Anwar M, Mehta D. Post-translational modifications of S1PR1 and endothelial barrier regulation. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158760. [PMID: 32585303 PMCID: PMC7409382 DOI: 10.1016/j.bbalip.2020.158760] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 06/09/2020] [Accepted: 06/15/2020] [Indexed: 12/16/2022]
Abstract
Sphingosine-1-phosphate receptor-1 (S1PR1), a G-protein coupled receptor that is expressed in endothelium and activated upon ligation by the bioactive lipid sphingosine-1-phosphate (S1P), is an important vascular-barrier protective mechanism at the level of adherens junctions (AJ). Loss of endothelial barrier function is a central factor in the pathogenesis of various inflammatory conditions characterized by protein-rich lung edema formation, such as acute respiratory distress syndrome (ARDS). While several S1PR1 agonists are available, the challenge of arresting the progression of protein-rich edema formation remains to be met. In this review, we discuss the role of S1PRs, especially S1PR1, in regulating endothelial barrier function. We review recent findings showing that replenishment of the pool of cell-surface S1PR1 may be crucial to the effectiveness of S1P in repairing the endothelial barrier. In this context, we discuss the S1P generating machinery and mechanisms that regulate S1PR1 at the cell surface and their impact on endothelial barrier function.
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Affiliation(s)
- Mumtaz Anwar
- Department of Pharmacology and Center for Lung and Vascular Biology, University of Illinois at Chicago Chicago, IL 60612, United States of America
| | - Dolly Mehta
- Department of Pharmacology and Center for Lung and Vascular Biology, University of Illinois at Chicago Chicago, IL 60612, United States of America.
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7
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Pulkoski-Gross MJ, Jenkins ML, Truman JP, Salama MF, Clarke CJ, Burke JE, Hannun YA, Obeid LM. An intrinsic lipid-binding interface controls sphingosine kinase 1 function. J Lipid Res 2018; 59:462-474. [PMID: 29326159 DOI: 10.1194/jlr.m081307] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 01/04/2018] [Indexed: 12/15/2022] Open
Abstract
Sphingosine kinase 1 (SK1) is required for production of sphingosine-1-phosphate (S1P) and thereby regulates many cellular processes, including cellular growth, immune cell trafficking, and inflammation. To produce S1P, SK1 must access sphingosine directly from membranes. However, the molecular mechanisms underlying SK1's direct membrane interactions remain unclear. We used hydrogen/deuterium exchange MS to study interactions of SK1 with membrane vesicles. Using the CRISPR/Cas9 technique to generate HCT116 cells lacking SK1, we explored the effects of membrane interface disruption and the function of the SK1 interaction site. Disrupting the interface resulted in reduced membrane association and decreased cellular SK1 activity. Moreover, SK1-dependent signaling, including cell invasion and endocytosis, was abolished upon mutation of the membrane-binding interface. Of note, we identified a positively charged motif on SK1 that is responsible for electrostatic interactions with membranes. Furthermore, we demonstrated that SK1 uses a single contiguous interface, consisting of an electrostatic site and a hydrophobic site, to interact with membrane-associated anionic phospholipids. Altogether, these results define a composite domain in SK1 that regulates its intrinsic ability to bind membranes and indicate that this binding is critical for proper SK1 function. This work will allow for a new line of thinking for targeting SK1 in disease.
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Affiliation(s)
- Michael J Pulkoski-Gross
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11790.,Department of Medicine and Stony Brook Cancer Center, Stony Brook University, Stony Brook, NY 11790
| | - Meredith L Jenkins
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8N 1A1, Canada
| | - Jean-Philip Truman
- Department of Medicine and Stony Brook Cancer Center, Stony Brook University, Stony Brook, NY 11790
| | - Mohamed F Salama
- Department of Biochemistry, Faculty of Veterinary Medicine, Mansoura University, Mansoura 35511, Egypt
| | - Christopher J Clarke
- Department of Medicine and Stony Brook Cancer Center, Stony Brook University, Stony Brook, NY 11790
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8N 1A1, Canada
| | - Yusuf A Hannun
- Department of Medicine and Stony Brook Cancer Center, Stony Brook University, Stony Brook, NY 11790
| | - Lina M Obeid
- Department of Medicine and Stony Brook Cancer Center, Stony Brook University, Stony Brook, NY 11790 .,Northport Veterans Affairs Medical Center, Northport, NY 11768
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8
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Arish M, Alaidarous M, Ali R, Akhter Y, Rub A. Implication of sphingosine-1-phosphate signaling in diseases: molecular mechanism and therapeutic strategies. J Recept Signal Transduct Res 2017; 37:437-446. [PMID: 28758826 DOI: 10.1080/10799893.2017.1358282] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Sphingosine-1-phosphate signaling is emerging as a critical regulator of cellular processes that is initiated by the intracellular production of bioactive lipid molecule, sphingosine-1-phosphate. Binding of sphingosine-1-phosphate to its extracellular receptors activates diverse downstream signaling that play a critical role in governing physiological processes. Increasing evidence suggests that this signaling pathway often gets impaired during pathophysiological and diseased conditions and hence manipulation of this signaling pathway may be beneficial in providing treatment. In this review, we summarized the recent findings of S1P signaling pathway and the versatile role of the participating candidates in context with several disease conditions. Finally, we discussed its possible role as a novel drug target in different diseases.
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Affiliation(s)
- Mohd Arish
- a Infection and Immunity Lab, Department of Biotechnology , Jamia Millia Islamia (A Central University) , New Delhi , India
| | - Mohammed Alaidarous
- b Department of Medical Laboratory Sciences, College of Applied Medical Sciences , Majmaah University , Al Majmaah , Saudi Arabia
| | - Rahat Ali
- a Infection and Immunity Lab, Department of Biotechnology , Jamia Millia Islamia (A Central University) , New Delhi , India
| | - Yusuf Akhter
- c Centre for Computational Biology & Bioinformatics, School of Life Sciences , Central University of Himachal Pradesh , Shahpur, Kangra , India
| | - Abdur Rub
- a Infection and Immunity Lab, Department of Biotechnology , Jamia Millia Islamia (A Central University) , New Delhi , India.,b Department of Medical Laboratory Sciences, College of Applied Medical Sciences , Majmaah University , Al Majmaah , Saudi Arabia
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9
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Mo ZC, Ren K, Liu X, Tang ZL, Yi GH. A high-density lipoprotein-mediated drug delivery system. Adv Drug Deliv Rev 2016; 106:132-147. [PMID: 27208399 DOI: 10.1016/j.addr.2016.04.030] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 04/13/2016] [Accepted: 04/27/2016] [Indexed: 01/08/2023]
Abstract
High-density lipoprotein (HDL) is a comparatively dense and small lipoprotein that can carry lipids as a multifunctional aggregate in plasma. Several studies have shown that increasing the levels or improving the functionality of HDL is a promising target for treating a wide variety of diseases. Among lipoproteins, HDL particles possess unique physicochemical properties, including naturally synthesized physiological components, amphipathic apolipoproteins, lipid-loading and hydrophobic agent-incorporating characteristics, specific protein-protein interactions, heterogeneity, nanoparticles, and smaller size. Recently, the feasibility and superiority of using HDL particles as drug delivery vehicles have been of great interest. In this review, we summarize the structure, constituents, biogenesis, remodeling, and reconstitution of HDL drug delivery systems, focusing on their delivery capability, characteristics, applications, manufacturing, and drug-loading and drug-targeting characteristics. Finally, the future prospects are presented regarding the clinical application and challenges of using HDL as a pharmacodelivery carrier.
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Affiliation(s)
- Zhong-Cheng Mo
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, Hengyang City 421001, Hunan Province, China; Department of Histology and Embryology, University of South China, Hengyang, Hunan 421001, China
| | - Kun Ren
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, Hengyang City 421001, Hunan Province, China
| | - Xing Liu
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, 100005 Beijing, China
| | - Zhen-Li Tang
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, Hengyang City 421001, Hunan Province, China
| | - Guang-Hui Yi
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, Hengyang City 421001, Hunan Province, China.
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10
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Zamora-Pineda J, Kumar A, Suh JH, Zhang M, Saba JD. Dendritic cell sphingosine-1-phosphate lyase regulates thymic egress. J Exp Med 2016; 213:2773-2791. [PMID: 27810923 PMCID: PMC5110016 DOI: 10.1084/jem.20160287] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 09/09/2016] [Indexed: 11/30/2022] Open
Abstract
Saba and collaborators show that dendritic cells generate the thymic sphingosine-1-phosphate gradient and regulate T cell egress. T cell egress from the thymus is essential for adaptive immunity and involves chemotaxis along a sphingosine-1-phosphate (S1P) gradient. Pericytes at the corticomedullary junction produce the S1P egress signal, whereas thymic parenchymal S1P levels are kept low through S1P lyase (SPL)–mediated metabolism. Although SPL is robustly expressed in thymic epithelial cells (TECs), in this study, we show that deleting SPL in CD11c+ dendritic cells (DCs), rather than TECs or other stromal cells, disrupts the S1P gradient, preventing egress. Adoptive transfer of peripheral wild-type DCs rescued the egress phenotype of DC-specific SPL knockout mice. These studies identify DCs as metabolic gatekeepers of thymic egress. Combined with their role as mediators of central tolerance, DCs are thus poised to provide homeostatic regulation of thymic export.
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Affiliation(s)
- Jesus Zamora-Pineda
- Center for Cancer Research, University of California, San Francisco Benioff Children's Hospital, Oakland, CA 94609
| | - Ashok Kumar
- Center for Cancer Research, University of California, San Francisco Benioff Children's Hospital, Oakland, CA 94609
| | - Jung H Suh
- Center for Cancer Research, University of California, San Francisco Benioff Children's Hospital, Oakland, CA 94609
| | - Meng Zhang
- Center for Cancer Research, University of California, San Francisco Benioff Children's Hospital, Oakland, CA 94609
| | - Julie D Saba
- Center for Cancer Research, University of California, San Francisco Benioff Children's Hospital, Oakland, CA 94609
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11
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Sphingosine 1-Phosphate Activation of EGFR As a Novel Target for Meningitic Escherichia coli Penetration of the Blood-Brain Barrier. PLoS Pathog 2016; 12:e1005926. [PMID: 27711202 PMCID: PMC5053521 DOI: 10.1371/journal.ppat.1005926] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 09/11/2016] [Indexed: 12/24/2022] Open
Abstract
Central nervous system (CNS) infection continues to be an important cause of mortality and morbidity, necessitating new approaches for investigating its pathogenesis, prevention and therapy. Escherichia coli is the most common Gram-negative bacillary organism causing meningitis, which develops following penetration of the blood-brain barrier (BBB). By chemical library screening, we identified epidermal growth factor receptor (EGFR) as a contributor to E. coli invasion of the BBB in vitro. Here, we obtained the direct evidence that CNS-infecting E. coli exploited sphingosine 1-phosphate (S1P) for EGFR activation in penetration of the BBB in vitro and in vivo. We found that S1P was upstream of EGFR and participated in EGFR activation through S1P receptor as well as through S1P-mediated up-regulation of EGFR-related ligand HB-EGF, and blockade of S1P function through targeting sphingosine kinase and S1P receptor inhibited EGFR activation, and also E. coli invasion of the BBB. We further found that both S1P and EGFR activations occurred in response to the same E. coli proteins (OmpA, FimH, NlpI), and that S1P and EGFR promoted E. coli invasion of the BBB by activating the downstream c-Src. These findings indicate that S1P and EGFR represent the novel host targets for meningitic E. coli penetration of the BBB, and counteracting such targets provide a novel approach for controlling E. coli meningitis in the era of increasing resistance to conventional antibiotics.
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12
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Tran HB, Barnawi J, Ween M, Hamon R, Roscioli E, Hodge G, Reynolds PN, Pitson SM, Davies LT, Haberberger R, Hodge S. Cigarette smoke inhibits efferocytosis via deregulation of sphingosine kinase signaling: reversal with exogenous S1P and the S1P analogue FTY720. J Leukoc Biol 2016; 100:195-202. [PMID: 26792820 DOI: 10.1189/jlb.3a1015-471r] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 01/04/2016] [Indexed: 12/31/2022] Open
Abstract
Alveolar macrophages from chronic obstructive pulmonary disease patients and cigarette smokers are deficient in their ability to phagocytose apoptotic bronchial epithelial cells (efferocytosis). We hypothesized that the defect is mediated via inhibition of sphingosine kinases and/or their subcellular mislocalization in response to cigarette smoke and can be normalized with exogenous sphingosine-1-phosphate or FTY720 (fingolimod), a modulator of sphingosine-1-phosphate signaling, which has been shown to be clinically useful in multiple sclerosis. Measurement of sphingosine kinase 1/2 activities by [(32)P]-labeled sphingosine-1-phosphate revealed a 30% reduction of sphingosine kinase 1 (P < 0.05) and a nonsignificant decrease of sphingosine kinase 2 in THP-1 macrophages after 1 h cigarette smoke extract exposure. By confocal analysis macrophage sphingosine kinase 1 protein was normally localized to the plasma membrane and cytoplasm and sphingosine kinase 2 to the nucleus and cytoplasm but absent at the cell surface. Cigarette smoke extract exposure (24 h) led to a retraction of sphingosine kinase 1 from the plasma membrane and sphingosine kinase 1/2 clumping in the Golgi domain. Selective inhibition of sphingosine kinase 2 with 25 µM ABC294640 led to 36% inhibition of efferocytosis (P < 0.05); 10 µM sphingosine kinase inhibitor/5C (sphingosine kinase 1-selective inhibitor) induced a nonsignificant inhibition of efferocytosis, but its combination with ABC294640 led to 56% inhibition (P < 0.01 vs. control and < 0.05 vs. single inhibitors). Cigarette smoke-inhibited efferocytosis was significantly (P < 0.05) reversed to near-control levels in the presence of 10-100 nM exogenous sphingosine-1-phosphate or FTY720, and FTY720 reduced cigarette smoke-induced clumping of sphingosine kinase 1/2 in the Golgi domain. These data strongly support a role of sphingosine kinase 1/2 in efferocytosis and as novel therapeutic targets in chronic obstructive pulmonary disease.
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Affiliation(s)
- Hai B Tran
- Lung Research Unit, Hanson Institute and Department of Thoracic Medicine, Royal Adelaide Hospital, Adelaide, Australia;
| | - Jameel Barnawi
- Lung Research Unit, Hanson Institute and Department of Thoracic Medicine, Royal Adelaide Hospital, Adelaide, Australia; Department of Medicine, University of Adelaide, Australia; Department of Medical Laboratory Technology, University of Tabuk, Saudi Arabia
| | - Miranda Ween
- Lung Research Unit, Hanson Institute and Department of Thoracic Medicine, Royal Adelaide Hospital, Adelaide, Australia
| | - Rhys Hamon
- Lung Research Unit, Hanson Institute and Department of Thoracic Medicine, Royal Adelaide Hospital, Adelaide, Australia
| | - Eugene Roscioli
- Lung Research Unit, Hanson Institute and Department of Thoracic Medicine, Royal Adelaide Hospital, Adelaide, Australia
| | - Greg Hodge
- Lung Research Unit, Hanson Institute and Department of Thoracic Medicine, Royal Adelaide Hospital, Adelaide, Australia; Department of Medicine, University of Adelaide, Australia
| | - Paul N Reynolds
- Lung Research Unit, Hanson Institute and Department of Thoracic Medicine, Royal Adelaide Hospital, Adelaide, Australia; Department of Medicine, University of Adelaide, Australia
| | - Stuart M Pitson
- Department of Medicine, University of Adelaide, Australia; Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, Australia; and
| | - Lorena T Davies
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, Australia; and
| | - Rainer Haberberger
- Centre for Neuroscience Anatomy and Histology, Flinders University, Adelaide, Australia
| | - Sandra Hodge
- Lung Research Unit, Hanson Institute and Department of Thoracic Medicine, Royal Adelaide Hospital, Adelaide, Australia; Department of Medicine, University of Adelaide, Australia;
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Arish M, Husein A, Kashif M, Saleem M, Akhter Y, Rub A. Sphingosine-1-phosphate signaling: unraveling its role as a drug target against infectious diseases. Drug Discov Today 2015; 21:133-142. [PMID: 26456576 DOI: 10.1016/j.drudis.2015.09.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 09/23/2015] [Accepted: 09/29/2015] [Indexed: 12/25/2022]
Abstract
Sphingosine-1-phosphate (S1P) signaling is reported in variety of cell types, including immune, endothelial and cancerous cells. It is emerging as a crucial regulator of cellular processes, such as apoptosis, cell proliferation, migration, differentiation and so on. This signaling pathway is initiated by the intracellular production and secretion of S1P through a cascade of enzymatic reactions. Binding of S1P to different S1P receptors (S1PRs) activates different downstream signaling pathways that regulate the cellular functions differentially depending upon the cell type. An accumulating body of evidence suggests that S1P metabolism and signaling is often impaired during infectious diseases; thus, its manipulation might be helpful in the treatment of such diseases. In this review, we summarize recent advances in our understanding of the S1P signaling pathway and its candidature as a novel drug target against infectious diseases.
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Affiliation(s)
- Mohd Arish
- Infection and Immunity Lab, Department of Biotechnology, Jamia Millia Islamia (A Central University), New Delhi 110025, India
| | - Atahar Husein
- Infection and Immunity Lab, Department of Biotechnology, Jamia Millia Islamia (A Central University), New Delhi 110025, India
| | - Mohammad Kashif
- Infection and Immunity Lab, Department of Biotechnology, Jamia Millia Islamia (A Central University), New Delhi 110025, India
| | - Mohammed Saleem
- Department of Life Sciences, National Institute of Technology, Rourkela, Odisha 769008, India
| | - Yusuf Akhter
- School of Life Sciences, Central University of Himachal Pradesh, Temporary Academic Block, Shahpur, Kangra, HP 176216, India
| | - Abdur Rub
- Infection and Immunity Lab, Department of Biotechnology, Jamia Millia Islamia (A Central University), New Delhi 110025, India.
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14
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Wilson PC, Fitzgibbon WR, Garrett SM, Jaffa AA, Luttrell LM, Brands MW, El-Shewy HM. Inhibition of Sphingosine Kinase 1 Ameliorates Angiotensin II-Induced Hypertension and Inhibits Transmembrane Calcium Entry via Store-Operated Calcium Channel. Mol Endocrinol 2015; 29:896-908. [PMID: 25871850 DOI: 10.1210/me.2014-1388] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Angiotensin II (AngII) plays a critical role in the regulation of vascular tone and blood pressure mainly via regulation of Ca(2+) mobilization. Several reports have implicated sphingosine kinase 1 (SK1)/sphingosine 1-phosphate (S1P) in the mobilization of intracellular Ca(2+) through a yet-undefined mechanism. Here we demonstrate that AngII-induces biphasic calcium entry in vascular smooth muscle cells, consisting of an immediate peak due to inositol tris-phosphate-dependent release of intracellular calcium, followed by a sustained transmembrane Ca(2+) influx through store-operated calcium channels (SOCs). Inhibition of SK1 attenuates the second phase of transmembrane Ca(2+) influx, suggesting a role for SK1 in AngII-dependent activation of SOC. Intracellular S1P triggers SOC-dependent Ca(2+) influx independent of S1P receptors, whereas external application of S1P stimulated S1P receptor-dependent Ca(2+) influx that is insensitive to inhibitors of SOCs, suggesting that the SK1/S1P axis regulates store-operated calcium entry via intracellular rather than extracellular actions. Genetic deletion of SK1 significantly inhibits both the acute hypertensive response to AngII in anaesthetized SK1 knockout mice and the sustained hypertensive response to continuous infusion of AngII in conscious animals. Collectively these data implicate SK1 as the missing link that connects the angiotensin AT1A receptor to transmembrane Ca(2+) influx and identify SOCs as a potential intracellular target for SK1.
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Affiliation(s)
- Parker C Wilson
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
| | - Wayne R Fitzgibbon
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
| | - Sara M Garrett
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
| | - Ayad A Jaffa
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
| | - Louis M Luttrell
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
| | - Michael W Brands
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
| | - Hesham M El-Shewy
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
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15
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Siow D, Sunkara M, Dunn TM, Morris AJ, Wattenberg B. ORMDL/serine palmitoyltransferase stoichiometry determines effects of ORMDL3 expression on sphingolipid biosynthesis. J Lipid Res 2015; 56:898-908. [PMID: 25691431 DOI: 10.1194/jlr.m057539] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The ORM1 (Saccharomyces cerevisiae)-like proteins (ORMDLs) and their yeast orthologs, the Orms, are negative homeostatic regulators of the initiating enzyme in sphingolipid biosynthesis, serine palmitoyltransferase (SPT). Genome-wide association studies have established a strong correlation between elevated expression of the endoplasmic reticulum protein ORMDL3 and risk for childhood asthma. Here we test the notion that elevated levels of ORMDL3 decrease sphingolipid biosynthesis. This was tested in cultured human bronchial epithelial cells (HBECs) (an immortalized, but untransformed, airway epithelial cell line) and in HeLa cells (a cervical adenocarcinoma cell line). Surprisingly, elevated ORMDL3 expression did not suppress de novo biosynthesis of sphingolipids. We determined that ORMDL is expressed in functional excess relative to SPT at normal levels of expression. ORMDLs and SPT form stable complexes that are not increased by elevated ORMDL3 expression. Although sphingolipid biosynthesis was not decreased by elevated ORMDL3 expression, the steady state mass levels of all major sphingolipids were marginally decreased by low level ORMDL3 over-expression in HBECs. These data indicate that the contribution of ORMDL3 to asthma risk may involve changes in sphingolipid metabolism, but that the connection is complex.
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Affiliation(s)
- Deanna Siow
- James Graham Brown Cancer Center University of Louisville School of Medicine, Louisville, KY 40202
| | - Manjula Sunkara
- Division of Cardiovascular Medicine, Gill Heart Institute, University of Kentucky Lexington and Department of Veterans Affairs Medical Center, Lexington, KY 40536
| | - Teresa M Dunn
- Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, MD 20184
| | - Andrew J Morris
- Division of Cardiovascular Medicine, Gill Heart Institute, University of Kentucky Lexington and Department of Veterans Affairs Medical Center, Lexington, KY 40536
| | - Binks Wattenberg
- James Graham Brown Cancer Center University of Louisville School of Medicine, Louisville, KY 40202 Departments of Medicine, Biochemistry, and Molecular Biology, Pharmacology, and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202
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Siow D, Sunkara M, Morris A, Wattenberg B. Regulation of de novo sphingolipid biosynthesis by the ORMDL proteins and sphingosine kinase-1. Adv Biol Regul 2014; 57:42-54. [PMID: 25319495 DOI: 10.1016/j.jbior.2014.09.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 09/03/2014] [Accepted: 09/04/2014] [Indexed: 12/11/2022]
Abstract
Sphingolipids are a diverse set of structurally and metabolically related lipids that have numerous functions in cell structure and signaling. The regulation of these lipids is critical for normal cell function and disregulation has been implicated in pathophysiological conditions such as cancer and inflammation. Here we examine control of the initiating, and rate limiting, enzyme in sphingolipid biosynthesis, serine palmitoyltransferase (SPT). We find that de novo synthesis of sphingolipid is stimulated by a number of cancer chemotherapeutics, suggesting that this may be an important aspect of their cytotoxic effects. The three ORMDL proteins are membrane proteins of the endoplasmic reticulum related to the yeast Orm proteins, which have been shown to be homeostatic regulators of SPT. We find that the ORMDL proteins are also negative regulators of SPT that transmit cellular levels of sphingolipids to SPT. The three isoforms have redundant functions in this system. The sphingosine kinases (sphingosine kinase-1 and -2) phosphorylate both sphingosine, which is released from ceramide, but also dihydrosphingosine, which is in the de novo biosynthetic pathway. We therefore examined the role of the sphingosine kinases in controlling de novo ceramide biosynthesis and find that sphingosine kinase-1 does indeed act as a negative regulator of this pathway. This establishes that sphingosine kinase, in addition to producing sphingosine-1-phosphate as a signaling molecule, also consumes dihydrosphingosine to regulate ceramide synthesis. Our studies demonstrate that there are multiple mechanisms of regulation of SPT and suggest that these regulators are important mediators of cell stress responses.
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Affiliation(s)
- Deanna Siow
- James Graham Brown Cancer Center, University of Louisville School of Medicine, 505 South Hancock St., Louisville, KY 40202, USA
| | - Manjula Sunkara
- Division of Cardiovascular Medicine, Gill Heart Institute, University of Kentucky Lexington, Lexington, KY 40536, USA; Department of Veterans Affairs Medical Center, Lexington, KY, USA
| | - Andrew Morris
- Division of Cardiovascular Medicine, Gill Heart Institute, University of Kentucky Lexington, Lexington, KY 40536, USA; Department of Veterans Affairs Medical Center, Lexington, KY, USA
| | - Binks Wattenberg
- James Graham Brown Cancer Center, University of Louisville School of Medicine, 505 South Hancock St., Louisville, KY 40202, USA; Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, 505 South Hancock St., Louisville, KY 40202, USA; Department of Pharmacology and Toxicology, University of Louisville School of Medicine, 505 South Hancock St., Louisville, KY 40202, USA.
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17
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Yagoub D, Wilkins MR, Lay AJ, Kaczorowski DC, Hatoum D, Bajan S, Hutvagner G, Lai JH, Wu W, Martiniello-Wilks R, Xia P, McGowan EM. Sphingosine kinase 1 isoform-specific interactions in breast cancer. Mol Endocrinol 2014; 28:1899-915. [PMID: 25216046 DOI: 10.1210/me.2013-1423] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Sphingosine kinase 1 (SK1) is a signaling enzyme that catalyzes the formation of sphingosine-1-phosphate. Overexpression of SK1 is causally associated with breast cancer progression and resistance to therapy. SK1 inhibitors are currently being investigated as promising breast cancer therapies. Two major transcriptional isoforms, SK143 kDa and SK151 kDa, have been identified; however, the 51 kDa variant is predominant in breast cancer cells. No studies have investigated the protein-protein interactions of the 51 kDa isoform and whether the two SK1 isoforms differ significantly in their interactions. Seeking an understanding of the regulation and role of SK1, we used a triple-labeling stable isotope labeling by amino acids in cell culture-based approach to identify SK1-interacting proteins common and unique to both isoforms. Of approximately 850 quantified proteins in SK1 immunoprecipitates, a high-confidence list of 30 protein interactions with each SK1 isoform was generated via a meta-analysis of multiple experimental replicates. Many of the novel identified SK1 interaction partners such as supervillin, drebrin, and the myristoylated alanine-rich C-kinase substrate-related protein supported and highlighted previously implicated roles of SK1 in breast cancer cell migration, adhesion, and cytoskeletal remodeling. Of these interactions, several were found to be exclusive to the 43 kDa isoform of SK1, including the protein phosphatase 2A, a previously identified SK1-interacting protein. Other proteins such as allograft inflammatory factor 1-like protein, the latent-transforming growth factor β-binding protein, and dipeptidyl peptidase 2 were found to associate exclusively with the 51 kDa isoform of SK1. In this report, we have identified common and isoform-specific SK1-interacting partners that provide insight into the molecular mechanisms that drive SK1-mediated oncogenicity.
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Affiliation(s)
- Daniel Yagoub
- School of Biotechnology and Biomolecular Sciences (D.Y., M.R.W.), University of New South Wales, Sydney 2052, Australia; Centenary Institute (D.Y., A.L., D.G.K., P.X., E.M.M.), Sydney 2042, Australia; Translational Cancer Research Group (D.H., R.M.-W., E.M.M.), Faculty of Science, School of Medical and Molecular Biosciences, and Faculty of Engineering and Information Technology (S.B., G.H.), University of Technology Sydney, Sydney, New South Wales 2007, Australia; Department of Biochemistry (J.H.L., W.W.), Tufts University School of Medicine, Boston, Massachusetts 02111; Shanghai Medical School (P.X.), Fudan University, 200433 Shanghai, People's Republic of China; and Sydney Medical School (E.M.M.), The University of Sydney, Sydney 2006, Australia
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18
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The histone deacetylase-6 inhibitor tubacin directly inhibits de novo sphingolipid biosynthesis as an off-target effect. Biochem Biophys Res Commun 2014; 449:268-71. [PMID: 24835950 DOI: 10.1016/j.bbrc.2014.05.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 05/06/2014] [Indexed: 11/21/2022]
Abstract
Histone deacetylase 6 (HDAC6) controls acetylation of a number of cytosolic proteins, most prominently tubulin. Tubacin is a small molecule inhibitor of HDAC6 selected for its selective inhibition of HDAC6 relative to other histone deacetylases. For this reason it has become a useful pharmacological tool to discern the biological functions of HDAC6 in numerous cellular processes. The interest of this laboratory is in the function and regulation of sphingolipids, a family of lipids based on the sphingosine backbone. Sphingolipid biosynthesis is initiated by the rate limiting enzyme serine palmitoyltransferase (SPT). Sphingolipids have critical and diverse functions in cell survival, apoptosis, intra- and intercellular signaling, and in membrane structure. In the course of examining the role of HDAC6 in the regulation of sphingolipid biosynthesis we observed that tubacin strongly inhibited de novo synthesis whereas HDAC6 knockdown very moderately stimulated synthesis. We resolved these seemingly contradictory results by demonstrating that, surprisingly, tubacin is a direct inhibitor of SPT activity in permeabilized cells. Furthermore tubacin inhibits de novo sphingolipid synthesis in intact cells at doses commonly used to test HDAC6 function and does so in an HDAC6-independent manner. Niltubacin is a chemical analog of tubacin which lacks tubacin's HDAC6 activity, and so is often used as a control for off-target effects of tubacin. We find that niltubacin is inactive in the inhibition of sphingolipid biosynthesis, and so does not serve to distinguish the inhibitory effects of tubacin on HDAC6 from those on sphingolipid biosynthesis. These results indicate that caution should be used in the use of tubacin to study the role of HDAC6.
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de la Garza-Rodea AS, Baldwin DM, Oskouian B, Place RF, Bandhuvula P, Kumar A, Saba JD. Sphingosine phosphate lyase regulates myogenic differentiation via S1P receptor-mediated effects on myogenic microRNA expression. FASEB J 2013; 28:506-19. [PMID: 24158395 DOI: 10.1096/fj.13-233155] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
S1P lyase (SPL) catalyzes the irreversible degradation of sphingosine-1-phosphate (S1P), a bioactive lipid whose signaling activities regulate muscle differentiation, homeostasis, and satellite cell (SC) activation. By regulating S1P levels, SPL also controls SC recruitment and muscle regeneration, representing a potential therapeutic target for muscular dystrophy. We found that SPL is induced during myoblast differentiation. To investigate SPL's role in myogenesis at the cellular level, we generated and characterized a murine myoblast SPL-knockdown (SPL-KD) cell line lacking SPL. SPL-KD cells accumulated intracellular and extracellular S1P and failed to form myotubes under conditions that normally stimulate myogenic differentiation. Under differentiation conditions, SPL-KD cells also demonstrated delayed induction of 3 myogenic microRNAs (miRNAs), miR-1, miR-206, and miR-486. SPL-KD cells successfully differentiated when treated with an S1P1 agonist, S1P2 antagonist, and combination treatments, which also increased myogenic miRNA levels. SPL-KD cells transfected with mimics for miR-1 or miR-206 also overcame the differentiation block. Thus, we show for the first time that the S1P/SPL/S1P-receptor axis regulates the expression of a number of miRNAs, thereby contributing to myogenic differentiation.
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Affiliation(s)
- Anabel S de la Garza-Rodea
- 1Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, CA 94609, USA.
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20
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The roles of sphingosine kinase 1 and 2 in regulating the metabolome and survival of prostate cancer cells. Biomolecules 2013; 3:316-33. [PMID: 24970170 PMCID: PMC4030851 DOI: 10.3390/biom3020316] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 06/03/2013] [Accepted: 06/04/2013] [Indexed: 12/15/2022] Open
Abstract
We have previously shown that treatment of androgen-sensitive LNCaP cells with the sphingosine kinase (SK) inhibitor SKi (2-(p-hydroxyanilino)-4-(p-chlorophenyl)thiazole) induces the proteasomal degradation of two N-terminal variants of SK1 (SK1a and SK1b), increases C22:0-ceramide and diadenosine 5′,5′′′-P1,P3-triphosphate (Ap3A) and reduces S1P levels, and promotes apoptosis. We have now investigated the effects of three SK inhibitors (SKi, (S)-FTY720 vinylphosphonate, and (R)-FTY720 methyl ether) on metabolite and sphingolipid levels in androgen-sensitive LNCaP and androgen-independent LNCaP-AI prostate cancer cells. The 51 kDa N-terminal variant of SK1 (SK1b) evades the proteasome in LNCaP-AI cells, and these cells do not exhibit an increase in C22:0-ceramide or Ap3A levels and do not undergo apoptosis in response to SKi. In contrast, the SK inhibitor (S)-FTY720 vinylphosphonate induces degradation of SK1b in LNCaP-AI, but not in LNCaP cells. In LNCaP-AI cells, (S)-FTY720 vinylphosphonate induces a small increase in C16:0-ceramide levels and cleavage of polyADPribose polymerase (indicative of apoptosis). Surprisingly, the level of S1P is increased by 7.8- and 12.8-fold in LNCaP and LNCaP-AI cells, respectively, on treatment with (S)-FTY720 vinylphosphonate. Finally, treatment of androgen-sensitive LNCaP cells with the SK2-selective inhibitor (R)-FTY720 methyl ether increases lysophosphatidylinositol levels, suggesting that SK2 may regulate lyso-PI metabolism in prostate cancer cells.
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Neubauer HA, Pitson SM. Roles, regulation and inhibitors of sphingosine kinase 2. FEBS J 2013; 280:5317-36. [PMID: 23638983 DOI: 10.1111/febs.12314] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 04/29/2013] [Accepted: 04/29/2013] [Indexed: 12/19/2022]
Abstract
The bioactive sphingolipids ceramide, sphingosine and sphingosine-1-phosphate (S1P) are important signalling molecules that regulate a diverse array of cellular processes. Most notably, the balance of the levels of these three sphingolipids in cells, termed the 'sphingolipid rheostat', can dictate cell fate, where ceramide and sphingosine enhance apoptosis and S1P promotes cell survival and proliferation. The sphingosine kinases (SKs) catalyse the production of S1P from sphingosine and are therefore central regulators of the sphingolipid rheostat and attractive targets for cancer therapy. Two SKs exist in humans: SK1 and SK2. SK1 has been extensively studied and there is a large body of evidence to demonstrate its role in promoting cell survival, proliferation and neoplastic transformation. SK1 is also elevated in many human cancers which appears to contribute to carcinogenesis, chemotherapeutic resistance and poor patient outcome. SK2, however, has not been as well characterized, and there are contradictions in the key physiological functions that have been proposed for this isoform. Despite this, many studies are now emerging that implicate SK2 in key roles in a variety of diseases, including the development of a range of solid tumours. Here, we review the literature examining SK2, its physiological and pathophysiological functions, the current knowledge of its regulation, and recent developments in targeting this complex enzyme.
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Affiliation(s)
- Heidi A Neubauer
- Centre for Cancer Biology, SA Pathology, Adelaide, Australia; School of Molecular and Biomedical Science, University of Adelaide, Australia
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22
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Post-translational regulation of sphingosine kinases. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:147-56. [DOI: 10.1016/j.bbalip.2012.07.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 07/04/2012] [Accepted: 07/06/2012] [Indexed: 12/22/2022]
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Siow DL, Wattenberg BW. Mammalian ORMDL proteins mediate the feedback response in ceramide biosynthesis. J Biol Chem 2012; 287:40198-204. [PMID: 23066021 DOI: 10.1074/jbc.c112.404012] [Citation(s) in RCA: 281] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND The yeast Orm1/2 proteins regulate ceramide biosynthesis. RESULTS Depletion of the mammalian Orm1/2 homologues, ORMDL1-3, eliminates the negative feedback of exogenous ceramide on ceramide biosynthesis in HeLa cells. CONCLUSION ORMDL proteins are the primary regulators of ceramide biosynthesis in mammalian cells. SIGNIFICANCE Therapeutically manipulating levels of the pro-death lipid, ceramide, requires a molecular understanding of its regulation. The mammalian ORMDL proteins are orthologues of the yeast Orm proteins (Orm1/2), which are regulators of ceramide biosynthesis. In mammalian cells, ceramide is a proapoptotic signaling sphingolipid, but it is also an obligate precursor to essential higher order sphingolipids. Therefore levels of ceramide are expected to be tightly controlled. We tested the three ORMDL isoforms for their role in homeostatically regulating ceramide biosynthesis in mammalian cells. Treatment of cells with a short chain (C6) ceramide or sphingosine resulted in a dramatic inhibition of ceramide biosynthesis. This inhibition was almost completely eliminated by ORMDL knockdown. This establishes that the ORMDL proteins mediate the feedback regulation of ceramide biosynthesis in mammalian cells. The ORMDL proteins are functionally redundant. Knockdown of all three isoforms simultaneously was required to alleviate the sphingolipid-mediated inhibition of ceramide biosynthesis. The lipid sensed by the ORMDL-mediated feedback mechanism is medium or long chain ceramide or a higher order sphingolipid. Treatment of permeabilized cells with C6-ceramide resulted in ORMDL-mediated inhibition of the rate-limiting enzyme in sphingolipid biosynthesis, serine palmitoyltransferase. This indicates that C6-ceramide inhibition requires only membrane-bound elements and does not involve diffusible proteins or small molecules. We also tested the atypical sphingomyelin synthase isoform, SMSr, for its role in the regulation of ceramide biosynthesis. This unusual enzyme has been reported to regulate ceramide levels in the endoplasmic reticulum. We were unable to detect a role for SMSr in regulating ceramide biosynthesis. We suggest that the role of SMSr may be in the regulation of downstream metabolism of ceramide.
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Affiliation(s)
- Deanna L Siow
- James Graham Brown Cancer Center, Louisville, KY 40202, USA
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Newbigging S, Zhang M, Saba JD. Immunohistochemical analysis of sphingosine phosphate lyase expression during murine development. Gene Expr Patterns 2012; 13:21-9. [PMID: 23041657 DOI: 10.1016/j.gep.2012.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 09/24/2012] [Accepted: 09/25/2012] [Indexed: 01/06/2023]
Abstract
Sphingosine-1-phosphate lyase (SPL) catalyzes the degradation of sphingosine-1-phosphate (S1P), a bioactive lipid that controls cell proliferation, migration and survival. Mice lacking SPL expression exhibit developmental abnormalities, runting and death during the perinatal period, suggesting that SPL plays a role in mammalian development and adaptation to extrauterine life. We investigated the pattern of SPL expression in the mouse embryo and placenta from day 8 to day 18. Our findings reveal that SPL is expressed in the developing brain and neural tube, Rathke's pouch, first brachial arch, third brachial arch, optic stalk, midgut loops, and lung buds. Diffuse signal was high at E12, whereas a recognizable adult SPL pattern was evident by E15 and more intensely at E18, with strong expression in skin, nasal epithelium, intestinal epithelium, cartilage, thymus and pituitary gland. These findings suggest SPL may be involved in development of the mammalian central nervous system (CNS), anterior pituitary, trigeminal nerve, palate and facial bones, thymus and other organs. Our findings are consistent with the SPL expression pattern of the adult mouse and with congenital abnormalities observed in SPL mutant mice.
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Affiliation(s)
- Susan Newbigging
- Centre for Modeling Human Disease, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, The Toronto Centre for Phenogenomics, University of Toronto, Toronto, Ontario, Canada
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Orr Gandy KA, Obeid LM. Targeting the sphingosine kinase/sphingosine 1-phosphate pathway in disease: review of sphingosine kinase inhibitors. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:157-66. [PMID: 22801037 DOI: 10.1016/j.bbalip.2012.07.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/05/2012] [Accepted: 07/06/2012] [Indexed: 12/01/2022]
Abstract
Sphingosine 1-phosphate (S1P) is an important bioactive sphingolipid metabolite that has been implicated in numerous physiological and cellular processes. Not only does S1P play a structural role in cells by defining the components of the plasma membrane, but in the last 20 years it has been implicated in various significant cell signaling pathways and physiological processes: for example, cell migration, survival and proliferation, cellular architecture, cell-cell contacts and adhesions, vascular development, atherosclerosis, acute pulmonary injury and respiratory distress, inflammation and immunity, and tumorogenesis and metastasis [1,2]. Given the wide variety of cellular and physiological processes in which S1P is involved, it is immediately obvious why the mechanisms governing S1P synthesis and degradation, and the manner in which these processes are regulated, are necessary to understand. In gaining more knowledge about regulation of the sphingosine kinase (SK)/S1P pathway, many potential therapeutic targets may be revealed. This review explores the roles of the SK/S1P pathway in disease, summarizes available SK enzyme inhibitors and examines their potential as therapeutic agents. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.
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Affiliation(s)
- K Alexa Orr Gandy
- The Department of Molecular and Cellular Biology, The Medical University of South Carolina, Charleston, SC 29425, USA
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S1P lyase in skeletal muscle regeneration and satellite cell activation: exposing the hidden lyase. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:167-75. [PMID: 22750505 DOI: 10.1016/j.bbalip.2012.06.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 06/18/2012] [Accepted: 06/20/2012] [Indexed: 01/12/2023]
Abstract
Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid whose actions are essential for many physiological processes including angiogenesis, lymphocyte trafficking and development. In addition, S1P serves as a muscle trophic factor that enables efficient muscle regeneration. This is due in part to S1P's ability to activate quiescent muscle stem cells called satellite cells (SCs) that are needed for muscle repair. However, the molecular mechanism by which S1P activates SCs has not been well understood. Further, strategies for harnessing S1P signaling to recruit SCs for therapeutic benefit have been lacking. S1P is irreversibly catabolized by S1P lyase (SPL), a highly conserved enzyme that catalyzes the cleavage of S1P at carbon bond C(2-3), resulting in formation of hexadecenal and ethanolamine-phosphate. SPL enhances apoptosis through substrate- and product-dependent events, thereby regulating cellular responses to chemotherapy, radiation and ischemia. SPL is undetectable in resting murine skeletal muscle. However, we recently found that SPL is dynamically upregulated in skeletal muscle after injury. SPL upregulation occurred in the context of a tightly orchestrated genetic program that resulted in a transient S1P signal in response to muscle injury. S1P activated quiescent SCs via a sphingosine-1-phosphate receptor 2 (S1P2)/signal transducer and activator of transcription 3 (STAT3)-dependent pathway, thereby facilitating skeletal muscle regeneration. Mdx mice, which serve as a model for muscular dystrophy (MD), exhibited skeletal muscle SPL upregulation and S1P deficiency. Pharmacological SPL inhibition raised skeletal muscle S1P levels, enhanced SC recruitment and improved mdx skeletal muscle regeneration. These findings reveal how S1P can activate SCs and indicate that SPL suppression may provide a therapeutic strategy for myopathies. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.
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Shaping the landscape: metabolic regulation of S1P gradients. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:193-202. [PMID: 22735358 DOI: 10.1016/j.bbalip.2012.06.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 06/15/2012] [Accepted: 06/17/2012] [Indexed: 12/11/2022]
Abstract
Sphingosine-1-phosphate (S1P) is a lipid that functions as a metabolic intermediate and a cellular signaling molecule. These roles are integrated when compartments with differing extracellular S1P concentrations are formed that serve to regulate functions within the immune and vascular systems, as well as during pathologic conditions. Gradients of S1P concentration are achieved by the organization of cells with specialized expression of S1P metabolic pathways within tissues. S1P concentration gradients underpin the ability of S1P signaling to regulate in vivo physiology. This review will discuss the mechanisms that are necessary for the formation and maintenance of S1P gradients, with the aim of understanding how a simple lipid controls complex physiology. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.
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Carr JM, Mahalingam S, Bonder CS, Pitson SM. Sphingosine kinase 1 in viral infections. Rev Med Virol 2012; 23:73-84. [PMID: 22639116 DOI: 10.1002/rmv.1718] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Revised: 03/19/2012] [Accepted: 03/22/2012] [Indexed: 12/24/2022]
Abstract
Sphingosine kinase 1 (SphK1) is an enzyme that phosphorylates the lipid sphingosine to generate sphingosine-1-phosphate (S1P). S1P can act intracellularly as a signaling molecule and extracellularly as a receptor ligand. The SphK1/S1P axis has well-described roles in cell signaling, the cell death/survival decision, the production of a pro-inflammatory response, immunomodulation, and control of vascular integrity. Agents targeting the SphK1/S1P axis are being actively developed as therapeutics for cancer and immunological and inflammatory disorders. Control of cell death/survival and pro-inflammatory immune responses is central to the pathology of infectious disease, and we can capitalize on the knowledge provided by investigations of SphK1/S1P in cancer and immunology to assess its application to selected human infections. We have herein reviewed the growing literature relating viral infections to changes in SphK1 and S1P. SphK1 activity is reportedly increased following human cytomegalovirus and respiratory syncytial virus infections, and elevated SphK1 enhances influenza virus infection. In contrast, SphK1 activity is reduced in bovine viral diarrhea virus and dengue virus infections. Sphingosine analogs that modulate S1P receptors have proven useful in animal models in alleviating influenza virus infection but have shown no benefit in simian human immunodeficiency virus and lymphocytic choriomeningitis virus infections. We have rationalized a role for SphK1/S1P in dengue virus, chikungunya virus, and Ross River virus infections, on the basis of the biology and the pathology of these diseases. The increasing number of effective SphK1 and S1P modulating agents currently in development makes it timely to investigate these roles with the potential for developing modulators of SphK1 and S1P for novel anti-viral therapies.
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Affiliation(s)
- Jillian M Carr
- Microbiology and Infectious Diseases, Flinders Medical Science and Technology, School of Medicine, Flinders University, Adelaide, South Australia, Australia.
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Sphingosine-1-phosphate signaling and its role in disease. Trends Cell Biol 2011; 22:50-60. [PMID: 22001186 DOI: 10.1016/j.tcb.2011.09.003] [Citation(s) in RCA: 781] [Impact Index Per Article: 60.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 09/08/2011] [Accepted: 09/09/2011] [Indexed: 02/07/2023]
Abstract
The bioactive sphingolipid metabolite sphingosine-1-phosphate (S1P) is now recognized as a critical regulator of many physiological and pathophysiological processes, including cancer, atherosclerosis, diabetes and osteoporosis. S1P is produced in cells by two sphingosine kinase isoenzymes, SphK1 and SphK2. Many cells secrete S1P, which can then act in an autocrine or paracrine manner. Most of the known actions of S1P are mediated by a family of five specific G protein-coupled receptors. More recently, it was shown that S1P also has important intracellular targets involved in inflammation, cancer and Alzheimer's disease. This suggests that S1P actions are much more complex than previously thought, with important ramifications for development of therapeutics. This review highlights recent advances in our understanding of the mechanisms of action of S1P and its roles in disease.
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Merrill AH. Sphingolipid and glycosphingolipid metabolic pathways in the era of sphingolipidomics. Chem Rev 2011; 111:6387-422. [PMID: 21942574 PMCID: PMC3191729 DOI: 10.1021/cr2002917] [Citation(s) in RCA: 527] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Indexed: 12/15/2022]
Affiliation(s)
- Alfred H Merrill
- School of Biology, and the Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332-0230, USA.
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Siow D, Wattenberg B. The compartmentalization and translocation of the sphingosine kinases: mechanisms and functions in cell signaling and sphingolipid metabolism. Crit Rev Biochem Mol Biol 2011; 46:365-75. [PMID: 21864225 DOI: 10.3109/10409238.2011.580097] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Members of the sphingosine kinase (SK) family of lipid signaling enzymes, comprising SK1 and SK2 in humans, are receiving considerable attention for their roles in a number of physiological and pathophysiological processes. The SKs are considered signaling enzymes based on their production of the potent lipid second messenger sphingosine-1-phosphate, which is the ligand for a family of five G-protein-linked receptors. Both SK1 and SK2 are intracellular enzymes and do not possess obvious membrane anchor domains within their primary sequences. The native substrates (sphingosine and dihydrosphingosine) are lipids, as are the corresponding products, and therefore would have a propensity to be membrane associated, suggesting that specific membrane localization of the SKs could affect both access to substrate and localized production of product. Here, we consider the emerging picture of the SKs as enzymes localized to specific intracellular sites, sometimes by agonist-dependent translocation, the mechanism targeting these enzymes to those sites, and the functional consequence of that localization. Not only is the signaling output of the SKs affected by subcellular localization, but the role of these enzymes as metabolic regulators of sphingolipid metabolism may be impacted as well.
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Affiliation(s)
- Deanna Siow
- James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
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Bandhuvula P, Honbo N, Wang GY, Jin ZQ, Fyrst H, Zhang M, Borowsky AD, Dillard L, Karliner JS, Saba JD. S1P lyase: a novel therapeutic target for ischemia-reperfusion injury of the heart. Am J Physiol Heart Circ Physiol 2011; 300:H1753-61. [PMID: 21335477 DOI: 10.1152/ajpheart.00946.2010] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid that promotes cardiomyocyte survival and contributes to ischemic preconditioning. S1P lyase (SPL) is a stress-activated enzyme responsible for irreversible S1P catabolism. We hypothesized that SPL contributes to oxidative stress by depleting S1P pools available for cardioprotective signaling. Accordingly, we evaluated SPL inhibition as a strategy for reducing cardiac ischemia-reperfusion (I/R) injury. We measured SPL expression and enzyme activity in murine hearts. Basal SPL activity was low in wild-type cardiac tissue but was activated in response to 50 min of ischemia (n = 5, P < 0.01). Hearts of heterozygous SPL knockout mice exhibited reduced SPL activity, elevated S1P levels, smaller infarct size, and increased functional recovery after I/R compared with littermate controls (n = 5, P < 0.01). The small molecule tetrahydroxybutylimidazole (THI) is a Federal Drug Administration-approved food additive that inhibits SPL. When given overnight at 25 mg/l in drinking water, THI raised S1P levels and reduced SPL activity (n = 5, P < 0.01). THI reduced infarct size and enhanced hemodynamic recovery in response to 50 min of ischemia and to 40 min of reperfusion in ex vivo hearts (n = 7, P < .01). These data correlated with an increase in MAP kinase-interacting serine/threonine kinase 1, eukaryotic translation initiation factor 4E, and ribosomal protein S6 phosphorylation levels after I/R, suggesting that SPL inhibition enhances protein translation. Pretreatment with an S1P₁ and S1P₃ receptor antagonist partially reversed the effects of THI. These results reveal, for the first time, that SPL is an ischemia-induced enzyme that can be targeted as a novel strategy for preventing cardiac I/R injury.
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Pitson SM. Regulation of sphingosine kinase and sphingolipid signaling. Trends Biochem Sci 2011; 36:97-107. [DOI: 10.1016/j.tibs.2010.08.001] [Citation(s) in RCA: 217] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2010] [Revised: 08/16/2010] [Accepted: 08/16/2010] [Indexed: 01/09/2023]
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Chavez A, Smith M, Mehta D. New Insights into the Regulation of Vascular Permeability. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 290:205-48. [DOI: 10.1016/b978-0-12-386037-8.00001-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Wattenberg BW. Role of sphingosine kinase localization in sphingolipid signaling. World J Biol Chem 2010; 1:362-8. [PMID: 21537471 PMCID: PMC3083941 DOI: 10.4331/wjbc.v1.i12.362] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 10/22/2010] [Accepted: 10/29/2010] [Indexed: 02/05/2023] Open
Abstract
The sphingosine kinases, SK1 and SK2, produce the potent signaling lipid sphingosine-1-phosphate (S1P). These enzymes have garnered increasing interest for their roles in tumorigenesis, inflammation, vascular diseases, and immunity, as well as other functions. The sphingosine kinases are considered signaling enzymes by producing S1P, and their activity is acutely regulated by a variety of agonists. However, these enzymes are also key players in the control of sphingolipid metabolism. A variety of sphingolipids, such as sphingosine and the ceramides, are potent signaling molecules in their own right. The role of sphingosine kinases in regulating sphingolipid metabolism is potentially a critical aspect of their signaling function. A central aspect of signaling lipids is that their hydrophobic nature constrains them to membranes. Most enzymes of sphingolipid metabolism, including the enzymes that degrade S1P, are membrane enzymes. Therefore the localization of the sphingosine kinases and S1P is likely to be important in S1P signaling. Sphingosine kinase localization affects sphingolipid signaling in several ways. Translocation of SK1 to the plasma membrane promotes extracellular secretion of S1P. SK1 and SK2 localization to specific sites appears to direct S1P to intracellular protein effectors. SK localization also determines the access of these enzymes to their substrates. This may be an important mechanism for the regulation of ceramide biosynthesis by diverting dihydrosphingosine, a precursor in the ceramide biosynthetic pathway, from the de novo production of ceramide.
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Affiliation(s)
- Binks W Wattenberg
- Binks W Wattenberg, Clinical and Translational Research Building, Room 419, 505 South Hancock St. Louisville, KY 40202, United States
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Siow DL, Anderson CD, Berdyshev EV, Skobeleva A, Natarajan V, Pitson SM, Wattenberg BW. Sphingosine kinase localization in the control of sphingolipid metabolism. ACTA ACUST UNITED AC 2010; 51:229-44. [PMID: 21075134 DOI: 10.1016/j.advenzreg.2010.09.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 09/05/2010] [Indexed: 11/30/2022]
Abstract
The sphingosine kinases (sphingosine kinase-1 and -2) have been implicated in a variety of physiological functions. Discerning their mechanism of action is complicated because in addition to producing the potent lipid second messenger sphingosine-1-phosphate, sphingosine kinases, both by producing sphingosine-1-phosphate and consuming sphingosine, have profound effects on sphingolipid metabolism. Sphingosine kinase-1 translocates to the plasma membrane upon agonist stimulation and this translocation is essential for the pro-oncogenic properties of this enzyme. Many of the enzymes of sphingolipid metabolism, including the enzymes that degrade sphingosine-1-phosphate, are membrane bound with restricted subcellular distributions. In the work described here we explore how subcellular localization of sphingosine kinase-1 affects the downstream metabolism of sphingosine-1-phosphate and the access of sphingosine kinase to its substrates. We find, surprisingly, that restricting sphingosine kinase to either the plasma membrane or the endoplasmic reticulum has a negligible effect on the rate of degradation of the sphingosine-1-phosphate that is produced. This suggests that sphingosine-1-phosphate is rapidly transported between membranes. However we also find that cytosolic or endoplasmic-reticulum targeted sphingosine kinase expressed at elevated levels produces extremely high levels of dihydrosphingosine-1-phosphate. Dihydrosphingosine is a proximal precursor in ceramide biosynthesis. Our data indicate that sphingosine kinase can divert substrate from the ceramide de novo synthesis pathway. However plasma membrane-restricted sphingosine kinase cannot access the pool of dihydrosphingosine. Therefore whereas sphingosine kinase localization does not affect downstream metabolism of sphingosine-1-phosphate, localization has an important effect on the pools of substrate to which this key signaling enzyme has access.
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Affiliation(s)
- Deanna L Siow
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Louisville, Louisville, KY 40202, USA
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