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Komai M, Noda Y, Ikeda A, Kaneshiro N, Kamikubo Y, Sakurai T, Uehara T, Takasugi N. Nuclear SphK2/S1P signaling is a key regulator of ApoE production and Aβ uptake in astrocytes. J Lipid Res 2024; 65:100510. [PMID: 38280459 PMCID: PMC10907773 DOI: 10.1016/j.jlr.2024.100510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/29/2024] Open
Abstract
The link between changes in astrocyte function and the pathological progression of Alzheimer's disease (AD) has attracted considerable attention. Interestingly, activated astrocytes in AD show abnormalities in their lipid content and metabolism. In particular, the expression of apolipoprotein E (ApoE), a lipid transporter, is decreased. Because ApoE has anti-inflammatory and amyloid β (Aβ)-metabolizing effects, the nuclear receptors, retinoid X receptor (RXR) and LXR, which are involved in ApoE expression, are considered promising therapeutic targets for AD. However, the therapeutic effects of agents targeting these receptors are limited or vary considerably among groups, indicating the involvement of an unknown pathological factor that modifies astrocyte and ApoE function. Here, we focused on the signaling lipid, sphingosine-1-phosphate (S1P), which is mainly produced by sphingosine kinase 2 (SphK2) in the brain. Using astrocyte models, we found that upregulation of SphK2/S1P signaling suppressed ApoE induction by both RXR and LXR agonists. We also found that SphK2 activation reduced RXR binding to the APOE promoter region in the nucleus, suggesting the nuclear function of SphK2/S1P. Intriguingly, suppression of SphK2 activity by RNA knockdown or specific inhibitors upregulated lipidated ApoE induction. Furthermore, the induced ApoE facilitates Aβ uptake in astrocytes. Together with our previous findings that SphK2 activity is upregulated in AD brain and promotes Aβ production in neurons, these results indicate that SphK2/S1P signaling is a promising multifunctional therapeutic target for AD that can modulate astrocyte function by stabilizing the effects of RXR and LXR agonists, and simultaneously regulate neuronal pathogenesis.
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Affiliation(s)
- Masato Komai
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita, Okayama, Japan; Research Fellow of Japan Society for the Promotion of Science, Chiyoda, Tokyo, Japan
| | - Yuka Noda
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita, Okayama, Japan
| | - Atsuya Ikeda
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita, Okayama, Japan
| | - Nanaka Kaneshiro
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita, Okayama, Japan
| | - Yuji Kamikubo
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo, Tokyo, Japan
| | - Takashi Sakurai
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo, Tokyo, Japan
| | - Takashi Uehara
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita, Okayama, Japan
| | - Nobumasa Takasugi
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita, Okayama, Japan; Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo, Tokyo, Japan.
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Acid Sphingomyelinase Is a Modulator of Contextual Fear. Int J Mol Sci 2022; 23:ijms23063398. [PMID: 35328819 PMCID: PMC8954852 DOI: 10.3390/ijms23063398] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/14/2022] [Accepted: 03/18/2022] [Indexed: 11/23/2022] Open
Abstract
Acid sphingomyelinase (ASM) regulates a variety of physiological processes and plays an important role in emotional behavior. The role of ASM in fear-related behavior has not been investigated so far. Using transgenic mice overexpressing ASM (ASMtg) and ASM deficient mice, we studied whether ASM regulates fear learning and expression of cued and contextual fear in a classical fear conditioning paradigm, a model used to investigate specific attributes of post-traumatic stress disorder (PTSD). We show that ASM does not affect fear learning as both ASMtg and ASM deficient mice display unaltered fear conditioning when compared to wild-type littermates. However, ASM regulates the expression of contextual fear in a sex-specific manner. While ASM overexpression enhances the expression of contextual fear in both male and female mice, ASM deficiency reduces the expression of contextual fear specifically in male mice. The expression of cued fear, however, is not regulated by ASM as ASMtg and ASM deficient mice display similar tone-elicited freezing levels. This study shows that ASM modulates the expression of contextual fear but not of cued fear in a sex-specific manner and adds a novel piece of information regarding the involvement of ASM in hippocampal-dependent aversive memory.
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Song H, McEwen HP, Duncan T, Lee JY, Teo JD, Don AS. Sphingosine kinase 2 is essential for remyelination following cuprizone intoxication. Glia 2021; 69:2863-2881. [PMID: 34399014 DOI: 10.1002/glia.24074] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 08/03/2021] [Accepted: 08/05/2021] [Indexed: 01/16/2023]
Abstract
Therapeutics that promote oligodendrocyte survival and remyelination are needed to restore neurological function in demyelinating diseases. Sphingosine 1-phosphate (S1P) is an essential lipid metabolite that signals through five G-protein coupled receptors. S1P receptor agonists such as Fingolimod are valuable immunosuppressants used to treat multiple sclerosis, and promote oligodendrocyte survival. However, the role for endogenous S1P, synthesized by the enzyme sphingosine kinase 2 (SphK2), in oligodendrocyte survival and myelination has not been established. This study investigated the requirement for SphK2 in oligodendrocyte survival and remyelination using the cuprizone mouse model of acute demyelination, followed by spontaneous remyelination. Oligodendrocyte density did not differ between untreated wild-type (WT) and SphK2 knockout (SphK2-/- ) mice. However, cuprizone treatment caused significantly greater loss of mature oligodendrocytes in SphK2-/- compared to WT mice. Following cuprizone withdrawal, spontaneous remyelination occurred in WT but not SphK2-/- mice, even though progenitor and mature oligodendrocyte density increased in both genotypes. Levels of cytotoxic sphingosine and ceramide were higher in the corpus callosum of SphK2-/- mice, and in contrast to WT mice, did not decline following cuprizone withdrawal in SphK2-/- mice. We also observed a significant reduction in myelin thickness with aging in SphK2-/- compared to WT mice. These results provide the first evidence that SphK2, the dominant enzyme catalyzing S1P synthesis in the adult brain, is essential for remyelination following a demyelinating insult and myelin maintenance with aging. We propose that persistently high levels of sphingosine and ceramide, a direct consequence of SphK2 deficiency, may block remyelination.
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Affiliation(s)
- Huitong Song
- Centenary Institute, The University of Sydney, Camperdown, New South Wales, Australia
| | - Holly P McEwen
- Centenary Institute, The University of Sydney, Camperdown, New South Wales, Australia
| | - Thomas Duncan
- School of Medical Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Jun Yup Lee
- Centenary Institute, The University of Sydney, Camperdown, New South Wales, Australia
| | - Jonathan D Teo
- Centenary Institute, The University of Sydney, Camperdown, New South Wales, Australia
| | - Anthony S Don
- Centenary Institute, The University of Sydney, Camperdown, New South Wales, Australia.,School of Medical Sciences, The University of Sydney, Camperdown, New South Wales, Australia
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Couttas TA, Rustam YH, Song H, Qi Y, Teo JD, Chen J, Reid GE, Don AS. A Novel Function of Sphingosine Kinase 2 in the Metabolism of Sphinga-4,14-Diene Lipids. Metabolites 2020; 10:metabo10060236. [PMID: 32521763 PMCID: PMC7344861 DOI: 10.3390/metabo10060236] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 05/27/2020] [Accepted: 06/04/2020] [Indexed: 12/14/2022] Open
Abstract
The number, position, and configuration of double bonds in lipids affect membrane fluidity and the recruitment of signaling proteins. Studies on mammalian sphingolipids have focused on those with a saturated sphinganine or mono-unsaturated sphingosine long chain base. Using high-resolution liquid chromatography-tandem mass spectrometry (LC-MS/MS), we observed a marked accumulation of lipids containing a di-unsaturated sphingadiene base in the hippocampus of mice lacking the metabolic enzyme sphingosine kinase 2 (SphK2). The double bonds were localized to positions C4–C5 and C14–C15 of sphingadiene using ultraviolet photodissociation-tandem mass spectrometry (UVPD-MS/MS). Phosphorylation of sphingoid bases by sphingosine kinase 1 (SphK1) or SphK2 forms the penultimate step in the lysosomal catabolism of all sphingolipids. Both SphK1 and SphK2 phosphorylated sphinga-4,14-diene as efficiently as sphingosine, however deuterated tracer experiments in an oligodendrocyte cell line demonstrated that ceramides with a sphingosine base are more rapidly metabolized than those with a sphingadiene base. Since SphK2 is the dominant sphingosine kinase in brain, we propose that the accumulation of sphingadiene-based lipids in SphK2-deficient brains results from the slower catabolism of these lipids, combined with a bottleneck in the catabolic pathway created by the absence of SphK2. We have therefore uncovered a previously unappreciated role for SphK2 in lipid quality control.
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Affiliation(s)
- Timothy Andrew Couttas
- Centenary Institute, The University of Sydney, Camperdown, NSW 2006, Australia; (T.A.C.); (H.S.); (Y.Q.); (J.D.T.); (J.C.)
| | - Yepy Hardi Rustam
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, VIC 3010, Australia; (Y.H.R.); (G.E.R.)
| | - Huitong Song
- Centenary Institute, The University of Sydney, Camperdown, NSW 2006, Australia; (T.A.C.); (H.S.); (Y.Q.); (J.D.T.); (J.C.)
| | - Yanfei Qi
- Centenary Institute, The University of Sydney, Camperdown, NSW 2006, Australia; (T.A.C.); (H.S.); (Y.Q.); (J.D.T.); (J.C.)
| | - Jonathan David Teo
- Centenary Institute, The University of Sydney, Camperdown, NSW 2006, Australia; (T.A.C.); (H.S.); (Y.Q.); (J.D.T.); (J.C.)
| | - Jinbiao Chen
- Centenary Institute, The University of Sydney, Camperdown, NSW 2006, Australia; (T.A.C.); (H.S.); (Y.Q.); (J.D.T.); (J.C.)
| | - Gavin Edmund Reid
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, VIC 3010, Australia; (Y.H.R.); (G.E.R.)
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Anthony Simon Don
- Centenary Institute, The University of Sydney, Camperdown, NSW 2006, Australia; (T.A.C.); (H.S.); (Y.Q.); (J.D.T.); (J.C.)
- NHMRC Clinical Trials Centre, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW 2006, Australia
- Correspondence: ; Tel.: +61-28627-5578
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Schroeder A, Nakamura JP, Hudson M, Jones NC, Du X, Sundram S, Hill RA. Raloxifene recovers effects of prenatal immune activation on cognitive task-induced gamma power. Psychoneuroendocrinology 2019; 110:104448. [PMID: 31546114 DOI: 10.1016/j.psyneuen.2019.104448] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/04/2019] [Accepted: 09/13/2019] [Indexed: 12/13/2022]
Abstract
There is currently no treatment available for the cognitive symptoms of schizophrenia, but evidence suggests that selective estrogen receptor modulators (SERMs) may provide relief. Our recent animal model data showed that a lack of female sex hormones in mice impairs the ability of hippocampal neurons to synchronise and generate oscillations within the frequency range of 30-80 Hz (gamma power) leading to cognitive impairment, while both estradiol and the SERM, raloxifene, recovered this. Given that cognitive impairment is accompanied by abnormal gamma power in schizophrenia, this study aimed to determine the effects of raloxifene on gamma power during spatial memory tasks in the prenatal immune challenged (poly-I:C) mouse model with relevance to schizophrenia. Pregnant dams received the viral mimetic poly-I:C (20 mg/kg, i.p.) at gestational day 17. Male and female offspring were treated with placebo or raloxifene implants at adulthood. Local field potentials from the CA1 hippocampus were simultaneously recorded during the Y-maze test of short term spatial memory and the cheeseboard maze test of long-term spatial learning and memory and cognitive flexibility. In female but not male mice, poly I:C exposure reduced gamma power during decision making and prolonged the time spent in the centre (decision making phase) during the Y-maze task. Female poly-I:C exposed mice also showed increased gamma power during acquisition of the cheeseboard long term memory task and perseverative behaviour. Treatment with raloxifene recovered gamma power and decision making deficits in the Y-maze and restored gamma power changes during the cheeseboard maze task as well as perseverative behaviour. Male mice showed no electrophysiological or behavioural effects of poly-I:C or raloxifene treatment. In summary, poly-I:C exposure induced female specific cognitive impairments accompanied by altered neural oscillations in the gamma frequency and raloxifene recovered these abnormalities.
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Affiliation(s)
- Anna Schroeder
- Psychoneuroendocrinology Laboratory, Florey Institute for Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3010, Australia; Behavioural Neuroscience Laboratory, Department of Psychiatry, School of Clinical Sciences, Monash University, 246 Clayton Rd, Clayton, VIC, 3168, Australia
| | - Jay P Nakamura
- Psychoneuroendocrinology Laboratory, Florey Institute for Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3010, Australia; Behavioural Neuroscience Laboratory, Department of Psychiatry, School of Clinical Sciences, Monash University, 246 Clayton Rd, Clayton, VIC, 3168, Australia
| | - Matthew Hudson
- Department of Medicine, University of Melbourne, Parkville, VIC, 3010, Australia; Department of Neuroscience, Monash University, Clayton, VIC, 3168, Australia
| | - Nigel C Jones
- Department of Medicine, University of Melbourne, Parkville, VIC, 3010, Australia; Department of Neuroscience, Monash University, Clayton, VIC, 3168, Australia
| | - Xin Du
- Psychoneuroendocrinology Laboratory, Florey Institute for Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3010, Australia; Behavioural Neuroscience Laboratory, Department of Psychiatry, School of Clinical Sciences, Monash University, 246 Clayton Rd, Clayton, VIC, 3168, Australia
| | - Suresh Sundram
- Behavioural Neuroscience Laboratory, Department of Psychiatry, School of Clinical Sciences, Monash University, 246 Clayton Rd, Clayton, VIC, 3168, Australia
| | - Rachel A Hill
- Psychoneuroendocrinology Laboratory, Florey Institute for Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3010, Australia; Behavioural Neuroscience Laboratory, Department of Psychiatry, School of Clinical Sciences, Monash University, 246 Clayton Rd, Clayton, VIC, 3168, Australia.
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Sphingosine Kinase 2 Potentiates Amyloid Deposition but Protects against Hippocampal Volume Loss and Demyelination in a Mouse Model of Alzheimer's Disease. J Neurosci 2019; 39:9645-9659. [PMID: 31641049 DOI: 10.1523/jneurosci.0524-19.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 09/19/2019] [Accepted: 10/10/2019] [Indexed: 01/20/2023] Open
Abstract
Sphingosine 1-phosphate (S1P) is a potent vasculoprotective and neuroprotective signaling lipid, synthesized primarily by sphingosine kinase 2 (SK2) in the brain. We have reported pronounced loss of S1P and SK2 activity early in Alzheimer's disease (AD) pathogenesis, and an inverse correlation between hippocampal S1P levels and age in females, leading us to speculate that loss of S1P is a sensitizing influence for AD. Paradoxically, SK2 was reported to mediate amyloid β (Aβ) formation from amyloid precursor protein (APP) in vitro To determine whether loss of S1P sensitizes to Aβ-mediated neurodegeneration, we investigated whether SK2 deficiency worsens pathology and memory in male J20 (PDGFB-APPSwInd) mice. SK2 deficiency greatly reduced Aβ content in J20 mice, associated with significant improvements in epileptiform activity and cross-frequency coupling measured by hippocampal electroencephalography. However, several key measures of APPSwInd-dependent neurodegeneration were enhanced on the SK2-null background, despite reduced Aβ burden. These included hippocampal volume loss, oligodendrocyte attrition and myelin loss, and impaired performance in Y-maze and social novelty memory tests. Inhibition of the endosomal cholesterol exporter NPC1 greatly reduced sphingosine phosphorylation in glial cells, linking loss of SK2 activity and S1P in AD to perturbed endosomal lipid metabolism. Our findings establish SK2 as an important endogenous regulator of both APP processing to Aβ, and oligodendrocyte survival, in vivo These results urge greater consideration of the roles played by oligodendrocyte dysfunction and altered membrane lipid metabolic flux as drivers of neurodegeneration in AD.SIGNIFICANCE STATEMENT Genetic, neuropathological, and functional studies implicate both Aβ and altered lipid metabolism and/or signaling as key pathogenic drivers of Alzheimer's disease. In this study, we first demonstrate that the enzyme SK2, which generates the signaling lipid S1P, is required for Aβ formation from APP in vivo Second, we establish a new role for SK2 in the protection of oligodendrocytes and myelin. Loss of SK2 sensitizes to Aβ-mediated neurodegeneration by attenuating oligodendrocyte survival and promoting hippocampal atrophy, despite reduced Aβ burden. Our findings support a model in which Aβ-independent sensitizing influences such as loss of neuroprotective S1P are more important drivers of neurodegeneration than gross Aβ concentration or plaque density.
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7
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Wang G, Bieberich E. Sphingolipids in neurodegeneration (with focus on ceramide and S1P). Adv Biol Regul 2018; 70:51-64. [PMID: 30287225 PMCID: PMC6251739 DOI: 10.1016/j.jbior.2018.09.013] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 09/20/2018] [Accepted: 09/21/2018] [Indexed: 04/14/2023]
Abstract
For many decades, research on sphingolipids associated with neurodegenerative disease focused on alterations in glycosphingolipids, particularly glycosylceramides (cerebrosides), sulfatides, and gangliosides. This seemed quite natural since many of these glycolipids are constituents of myelin and accumulated in lipid storage diseases (sphingolipidoses) resulting from enzyme deficiencies in glycolipid metabolism. With the advent of recognizing ceramide and its derivative, sphingosine-1-phosphate (S1P), as key players in lipid cell signaling and regulation of cell death and survival, research focus shifted toward these two sphingolipids. Ceramide and S1P are invoked in a plethora of cell biological processes participating in neurodegeneration such as ER stress, autophagy, dysregulation of protein and lipid transport, exosome secretion and neurotoxic protein spreading, neuroinflammation, and mitochondrial dysfunction. Hence, it is timely to discuss various functions of ceramide and S1P in neurodegenerative disease and to define sphingolipid metabolism and cell signaling pathways as potential targets for therapy.
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Affiliation(s)
- Guanghu Wang
- Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Erhard Bieberich
- Department of Physiology, University of Kentucky, Lexington, KY, USA.
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Phan A, Thomas CI, Chakraborty M, Berry JA, Kamasawa N, Davis RL. Stromalin Constrains Memory Acquisition by Developmentally Limiting Synaptic Vesicle Pool Size. Neuron 2018; 101:103-118.e5. [PMID: 30503644 DOI: 10.1016/j.neuron.2018.11.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 08/24/2018] [Accepted: 11/01/2018] [Indexed: 12/14/2022]
Abstract
Stromalin, a cohesin complex protein, was recently identified as a novel memory suppressor gene, but its mechanism remained unknown. Here, we show that Stromalin functions as a negative regulator of synaptic vesicle (SV) pool size in Drosophila neurons. Stromalin knockdown in dopamine neurons during a critical developmental period enhances learning and increases SV pool size without altering the number of dopamine neurons, their axons, or synapses. The developmental effect of Stromalin knockdown persists into adulthood, leading to strengthened synaptic connections and enhanced olfactory memory acquisition in adult flies. Correcting the SV content in dopamine neuron axon terminals by impairing anterograde SV trafficking motor protein Unc104/KIF1A rescues the enhanced-learning phenotype in Stromalin knockdown flies. Our results identify a new mechanism for memory suppression and reveal that the size of the SV pool is controlled genetically and independent from other aspects of neuron structure and function through Stromalin.
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Affiliation(s)
- Anna Phan
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL 33458, USA
| | - Connon I Thomas
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - Molee Chakraborty
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL 33458, USA
| | - Jacob A Berry
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL 33458, USA
| | - Naomi Kamasawa
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - Ronald L Davis
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL 33458, USA.
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Zhong L, Jiang X, Zhu Z, Qin H, Dinkins MB, Kong JN, Leanhart S, Wang R, Elsherbini A, Bieberich E, Zhao Y, Wang G. Lipid transporter Spns2 promotes microglia pro-inflammatory activation in response to amyloid-beta peptide. Glia 2018; 67:498-511. [PMID: 30484906 DOI: 10.1002/glia.23558] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 08/31/2018] [Accepted: 10/22/2018] [Indexed: 12/29/2022]
Abstract
Accumulating evidence indicates that neuroinflammation contributes to the pathogenesis and exacerbation of neurodegenerative disorders, such as Alzheimer's disease (AD). Sphingosine-1-phosphate (S1P) is a pleiotropic bioactive lipid that regulates many pathophysiological processes including inflammation. We present evidence here that the spinster homolog 2 (Spns2), a S1P transporter, promotes microglia pro-inflammatory activation in vitro and in vivo. Spns2 knockout (Spns2KO) in primary cultured microglia resulted in significantly reduced levels of pro-inflammatory cytokines induced by lipopolysaccharide (LPS) and amyloid-beta peptide 1-42 oligomers (Aβ42) when compared with littermate controls. Fingolimod (FTY720), a S1P receptor 1 (S1PR1) functional antagonist and FDA approved drug for relapsing-remitting multiple sclerosis, partially blunted Aβ42-induced pro-inflammatory cytokine generation, suggesting that Spns2 promotes microglia pro-inflammatory activation through S1P-signaling. Spns2KO significantly reduced Aβ42-induced nuclear factor kappa B (NFκB) activity. S1P increased, while FTY720 dampened, Aβ42-induced NFκB activity, suggesting that Spns2 activates microglia inflammation through, at least partially, NFκB pathway. Spns2KO mouse brains showed significantly reduced Aβ42-induced microglia activation/accumulation and reduced levels of pro-inflammatory cytokines when compared with age-matched controls. More interestingly, Spns2KO ameliorated Aβ42-induced working memory deficit detected by Y-Maze. In summary, these results suggest that Spns2 promotes pro-inflammatory polarization of microglia and may play a crucial role in AD pathogenesis.
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Affiliation(s)
- Liansheng Zhong
- Department of Physiology, University of Kentucky, Lexington, Kentucky.,Department of Bioinformatics, Key Laboratory of Cell Biology of Ministry of Public Health, College of Life Sciences, China Medical University, Shenyang, China
| | - Xue Jiang
- Department of Physiology, University of Kentucky, Lexington, Kentucky.,Shengjing Hospital, China Medical University, Shenyang, Liaoning, China
| | - Zhihui Zhu
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Haiyan Qin
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Michael B Dinkins
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, Georgia
| | - Ji-Na Kong
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Silvia Leanhart
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, Georgia
| | - Rebecca Wang
- Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, Maryland
| | - Ahmed Elsherbini
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Erhard Bieberich
- Department of Physiology, University of Kentucky, Lexington, Kentucky.,Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, Georgia
| | - Yujie Zhao
- Department of Bioinformatics, Key Laboratory of Cell Biology of Ministry of Public Health, College of Life Sciences, China Medical University, Shenyang, China
| | - Guanghu Wang
- Department of Physiology, University of Kentucky, Lexington, Kentucky
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Dominguez G, Maddelein ML, Pucelle M, Nicaise Y, Maurage CA, Duyckaerts C, Cuvillier O, Delisle MB. Neuronal sphingosine kinase 2 subcellular localization is altered in Alzheimer's disease brain. Acta Neuropathol Commun 2018; 6:25. [PMID: 29615132 PMCID: PMC5883421 DOI: 10.1186/s40478-018-0527-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/19/2018] [Indexed: 12/27/2022] Open
Abstract
Background Alzheimer’s disease (AD) is characterized by the accumulation of β-amyloid (Aβ) peptides and hyperphosphorylated tau protein accompanied by neuronal loss. Aβ accumulation has been associated with an impaired sphingosine 1-phosphate (S1P) metabolism. S1P is generated by sphingosine kinases (SphKs), of which there are two isoenzymes SphK1 and SphK2, and degraded by the sphingosine 1-phosphate lyase (SPL). We previously reported, that both a decrease in SphK1 expression and an increase in SPL expression, correlated with amyloid deposits in the entorhinal cortex of AD brains, suggesting a global loss of pro-survival S1P in AD neurons. SphK2 contribution has also been examined in AD yielding to conflicting results that may reflect the complexity of SphK2 regulation. The subcellular localization of SphK2, hence the compartmentalization of generated S1P, is recognized to play a crucial role in dictating either its pro-survival or pro-apoptotic functions. We therefore aimed at studying the expression of SphK2 and notably its subcellular localization in brain tissues from patients with AD. Results We report that a decrease in SphK2 protein cytosolic expression correlated with the density of amyloid deposits in a cohort of 25 post-mortem brains. Interestingly, we observed that the equilibrium between cytoplasmic and nuclear SphK2 is disrupted and showed that SphK2 is preferentially localized in the nucleus in AD brain extracts as compared to control extracts, with a marked increase of cleaved SphK2. Conclusions Our results suggest that a shift in the subcellular localization of the S1P generating SphK2 may compromise the well established pro-survival cytosolic S1P by favoring the production of nuclear S1P associated with adverse effects in AD pathogenesis. Electronic supplementary material The online version of this article (10.1186/s40478-018-0527-z) contains supplementary material, which is available to authorized users.
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"Dicing and Splicing" Sphingosine Kinase and Relevance to Cancer. Int J Mol Sci 2017; 18:ijms18091891. [PMID: 28869494 PMCID: PMC5618540 DOI: 10.3390/ijms18091891] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 08/29/2017] [Accepted: 08/29/2017] [Indexed: 02/06/2023] Open
Abstract
Sphingosine kinase (SphK) is a lipid enzyme that maintains cellular lipid homeostasis. Two SphK isozymes, SphK1 and SphK2, are expressed from different chromosomes and several variant isoforms are expressed from each of the isozymes, allowing for the multi-faceted biological diversity of SphK activity. Historically, SphK1 is mainly associated with oncogenicity, however in reality, both SphK1 and SphK2 isozymes possess oncogenic properties and are recognized therapeutic targets. The absence of mutations of SphK in various cancer types has led to the theory that cancer cells develop a dependency on SphK signaling (hyper-SphK signaling) or “non-oncogenic addiction”. Here we discuss additional theories of SphK cellular mislocation and aberrant “dicing and splicing” as contributors to cancer cell biology and as key determinants of the success or failure of SphK/S1P (sphingosine 1 phosphate) based therapeutics.
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