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Carreira AC, Santos TC, Lone MA, Zupančič E, Lloyd-Evans E, de Almeida RFM, Hornemann T, Silva LC. Mammalian sphingoid bases: Biophysical, physiological and pathological properties. Prog Lipid Res 2019:100995. [PMID: 31445071 DOI: 10.1016/j.plipres.2019.100995] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 05/17/2019] [Accepted: 05/20/2019] [Indexed: 12/19/2022]
Abstract
Sphingoid bases encompass a group of long chain amino alcohols which form the essential structure of sphingolipids. Over the last years, these amphiphilic molecules were moving more and more into the focus of biomedical research due to their role as bioactive molecules. In fact, free sphingoid bases interact with specific receptors and target molecules and have been associated with numerous biological and physiological processes. In addition, they can modulate the biophysical properties of biological membranes. Several human diseases are related to pathological changes in the structure and metabolism of sphingoid bases. Yet, the mechanisms underlying their biological and pathophysiological actions remain elusive. Within this review, we aimed to summarize the current knowledge on the biochemical and biophysical properties of the most common sphingoid bases and to discuss their importance in health and disease.
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Affiliation(s)
- A C Carreira
- iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; Centro de Química e Bioquímica (CQB) e Centro de Química Estrutural (CQE), Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Campo Grande, 1749-016 Lisboa, Portugal; Sir Martin Evans Building, School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - T C Santos
- iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; Centro de Química-Física Molecular - Institute of Nanoscience and Nanotechnology (CQFM-IN) and IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal; Institute for Clinical Chemistry, University Hospital Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland
| | - M A Lone
- Institute for Clinical Chemistry, University Hospital Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland
| | - E Zupančič
- iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - E Lloyd-Evans
- Sir Martin Evans Building, School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - R F M de Almeida
- Centro de Química e Bioquímica (CQB) e Centro de Química Estrutural (CQE), Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Campo Grande, 1749-016 Lisboa, Portugal
| | - T Hornemann
- Institute for Clinical Chemistry, University Hospital Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland
| | - L C Silva
- iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; Centro de Química-Física Molecular - Institute of Nanoscience and Nanotechnology (CQFM-IN) and IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.
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Su X, Ye Y, Yang Y, Zhang K, Bai W, Chen H, Kang E, Kong C, He X. The Effect of SPTLC2 on Promoting Neuronal Apoptosis is Alleviated by MiR-124-3p Through TLR4 Signalling Pathway. Neurochem Res 2019; 44:2113-2122. [PMID: 31372925 DOI: 10.1007/s11064-019-02849-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/06/2019] [Accepted: 07/27/2019] [Indexed: 12/21/2022]
Abstract
To investigate the role and mechanism of microRNA-124-3p (miR-124-3p) and serine palmitoyltransferase long chain base subunit 2 (SPTLC2) in neuronal apoptosis induced by mechanical injury. Transient transfection was used to modify the expression of miR-124-3p and SPTLC2. After transfection, neuronal apoptosis was evaluated in an in vitro injury model of primary neurons using TUNEL staining and western blot. The correlation between miR-124-3p and SPTLC2 was identified through a dual luciferase reporter assay in HEK293 cells. A rescue experiment in primary neurons was performed to further confirm the result. To explore the downstream mechanisms, co-immunoprecipitation was performed to identify proteins that interact with SPTLC2 in toll-like receptor 4 (TLR4) signalling pathway. Subsequently, the relative expression levels of TLR4 pathway molecules were measured by western blot. Our results showed that increased miR-124-3p can inhibit neuronal apoptosis, which is opposite to the effect of SPTLC2. In addition, miR-124-3p was proved to negatively regulate SPTLC2 expression and suppress the apoptosis-promoting effect of SPTLC2 via the TLR4 signalling pathway.
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Affiliation(s)
- Xinhong Su
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 169 Changle Western Road, Xi'an, 710032, Shanxi, China
| | - Yuqin Ye
- Department of Neurosurgery, PLA 921rd Hospital, Changsha, 410000, Hunan, China
| | - Yongxiang Yang
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 169 Changle Western Road, Xi'an, 710032, Shanxi, China
| | - Kailiang Zhang
- Department of Orthopedic Surgery, Orthopedic Oncology Institute of Chinese PLA, Tangdu Hospital, Air Force Military Medical University, Xi'an, 710032, Shanxi, China
| | - Wei Bai
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 169 Changle Western Road, Xi'an, 710032, Shanxi, China
| | - Huijun Chen
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 169 Changle Western Road, Xi'an, 710032, Shanxi, China
| | - Enming Kang
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 169 Changle Western Road, Xi'an, 710032, Shanxi, China
| | - Chuiguang Kong
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 169 Changle Western Road, Xi'an, 710032, Shanxi, China
| | - Xiaosheng He
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 169 Changle Western Road, Xi'an, 710032, Shanxi, China.
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53
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The Lipid Status in Patients with Ulcerative Colitis: Sphingolipids are Disease-Dependent Regulated. J Clin Med 2019; 8:jcm8070971. [PMID: 31277430 PMCID: PMC6678307 DOI: 10.3390/jcm8070971] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/13/2019] [Accepted: 07/02/2019] [Indexed: 02/06/2023] Open
Abstract
The factors that contribute to the development of ulcerative colitis (UC), are still not fully identified. Disruption of the colon barrier is one of the first events leading to invasion of bacteria and activation of the immune system. The colon barrier is strongly influenced by sphingolipids. Sphingolipids impact cell-cell contacts and function as second messengers. We collected blood and colon tissue samples from UC patients and healthy controls and investigated the sphingolipids and other lipids by LC-MS/MS or LC-QTOFMS. The expression of enzymes of the sphingolipid pathway were determined by RT-PCR and immunohistochemistry. In inflamed colon tissue, the de novo-synthesis of sphingolipids is reduced, whereas lactosylceramides are increased. Reduction of dihydroceramides was due to posttranslational inhibition rather than altered serine palmitoyl transferase or ceramide synthase expression in inflamed colon tissue. Furthermore, in human plasma from UC-patients, several sphinglipids change significantly in comparison to healthy controls. Beside sphingolipids free fatty acids, lysophosphatidylcholines and triglycerides changed significantly in the blood of colitis patients dependent on the disease severity. Our data indicate that detraction of the sphingolipid de novo synthesis in colon tissue might be an important trigger for UC. Several lipids changed significantly in the blood, which might be used as biomarkers for disease control; however, diet-related variabilities need to be considered.
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54
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Teng W, Li Y, Du M, Lei X, Xie S, Ren F. Sulforaphane Prevents Hepatic Insulin Resistance by Blocking Serine Palmitoyltransferase 3-Mediated Ceramide Biosynthesis. Nutrients 2019; 11:E1185. [PMID: 31137828 PMCID: PMC6566605 DOI: 10.3390/nu11051185] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 05/22/2019] [Accepted: 05/23/2019] [Indexed: 12/20/2022] Open
Abstract
Sulforaphane (SFA), a naturally active isothiocyanate compound from cruciferous vegetables used in clinical trials for cancer treatment, was found to possess potency to alleviate insulin resistance. But its underlying molecular mechanisms are still incompletely understood. In this study, we assessed whether SFA could improve insulin sensitivity and glucose homeostasis both in vitro and in vivo by regulating ceramide production. The effects of SFA on glucose metabolism and expression levels of key proteins in the hepatic insulin signaling pathway were evaluated in insulin-resistant human hepatic carcinoma HepG2 cells. The results showed that SFA dose-dependently increased glucose uptake and intracellular glycogen content by regulating the insulin receptor substrate 1 (IRS-1)/protein kinase B (Akt) signaling pathway in insulin-resistant HepG2 cells. SFA also reduced ceramide contents and downregulated transcription of ceramide-related genes. In addition, knockdown of serine palmitoyltransferase 3 (SPTLC3) in HepG2 cells prevented ceramide accumulation and alleviated insulin resistance. Moreover, SFA treatment improved glucose tolerance and insulin sensitivity, inhibited SPTLC3 expression and hepatic ceramide production and reduced hepatic triglyceride content in vivo. We conclude that SFA recovers glucose homeostasis and improves insulin sensitivity by blocking ceramide biosynthesis through modulating SPTLC3, indicating that SFA may be a potential candidate for prevention and amelioration of hepatic insulin resistance via a ceramide-dependent mechanism.
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Affiliation(s)
- Wendi Teng
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Yuan Li
- Key Laboratory of Functional Dairy, Co-constructed by ministry of Education and Beijing Municipality, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Min Du
- Department of Animal Sciences, Washington State University, Pullman, WA 99164, USA.
| | - Xingen Lei
- Department of Animal Science, Cornell University, Ithaca, NY 14853, USA.
| | - Siyu Xie
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Fazheng Ren
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China.
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55
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Carreira AC, Santos TC, Lone MA, Zupančič E, Lloyd-Evans E, de Almeida RFM, Hornemann T, Silva LC. Mammalian sphingoid bases: Biophysical, physiological and pathological properties. Prog Lipid Res 2019; 75:100988. [PMID: 31132366 DOI: 10.1016/j.plipres.2019.100988] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 05/17/2019] [Accepted: 05/21/2019] [Indexed: 12/11/2022]
Abstract
Sphingoid bases encompass a group of long chain amino alcohols which form the essential structure of sphingolipids. Over the last years, these amphiphilic molecules were moving more and more into the focus of biomedical research due to their role as bioactive molecules. In fact, free sphingoid bases interact with specific receptors and target molecules, and have been associated with numerous biological and physiological processes. In addition, they can modulate the biophysical properties of biological membranes. Several human diseases are related to pathological changes in the structure and metabolism of sphingoid bases. Yet, the mechanisms underlying their biological and pathophysiological actions remain elusive. Within this review, we aimed to summarize the current knowledge on the biochemical and biophysical properties of the most common sphingoid bases and to discuss their importance in health and disease.
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Affiliation(s)
- A C Carreira
- iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, Lisboa 1649-003, Portugal; Centro de Química e Bioquímica (CQB) e Centro de Química Estrutural (CQE), Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Campo Grande, Lisboa 1749-016, Portugal; Sir Martin Evans Building, School of Biosciences, Cardiff University, Cardiff, UK
| | - T C Santos
- iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, Lisboa 1649-003, Portugal; Centro de Química-Física Molecular - Institute of Nanoscience and Nanotechnology (CQFM-IN), IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal; Institute for Clinical Chemistry, University Hospital Zurich, Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland
| | - M A Lone
- Institute for Clinical Chemistry, University Hospital Zurich, Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland
| | - E Zupančič
- iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, Lisboa 1649-003, Portugal
| | - E Lloyd-Evans
- Sir Martin Evans Building, School of Biosciences, Cardiff University, Cardiff, UK
| | - R F M de Almeida
- Centro de Química e Bioquímica (CQB) e Centro de Química Estrutural (CQE), Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Campo Grande, Lisboa 1749-016, Portugal
| | - T Hornemann
- Institute for Clinical Chemistry, University Hospital Zurich, Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland
| | - L C Silva
- iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, Lisboa 1649-003, Portugal; Centro de Química-Física Molecular - Institute of Nanoscience and Nanotechnology (CQFM-IN), IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.
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56
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A Novel Variant (Asn177Asp) in SPTLC2 Causing Hereditary Sensory Autonomic Neuropathy Type 1C. Neuromolecular Med 2019; 21:182-191. [PMID: 30955194 DOI: 10.1007/s12017-019-08534-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 04/01/2019] [Indexed: 12/11/2022]
Abstract
Hereditary sensory and autonomic neuropathy type 1 (HSAN1) is a rare, autosomal dominantly inherited, slowly progressive and length-dependent axonal peripheral neuropathy. HSAN1 is associated with several mutations in serine-palmitoyltransferase (SPT), the first enzyme in the de novo sphingolipid biosynthetic pathway. HSAN1 mutations alter the substrate specificity of SPT, which leads to the formation of 1-deoxysphingolipids, an atypical and neurotoxic subclass of sphingolipids. This study describes the clinical and neurophysiological phenotype of a German family with a novel SPTCL2 mutation (c.529A > G; N177D) associated with HSAN1 and the biochemical characterization of this mutation.) The mutaion was identified in five family members that segregated with the diesease. Patients were characterized genetically and clinically for neurophysiological function. Their plasma sphingolipid profiles were analyzed by LC-MS. The biochemical properties of the mutation were characterized in a cell-based activity assay. Affected family members showed elevated 1-deoxysphingolipid plasma levels. HEK293 cells expressing the N177D SPTLC2 mutant showed increased de novo 1-deoxysphingolipid formation, but also displayed elevated canonical SPT activity and increased C20 sphingoid base production. This study identifies the SPTLC2 N177D variant as a novel disease-causing mutation with increased 1-deoxySL formation and its association with a typical HSAN1 phenotype.
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57
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Triplett J, Nicholson G, Sue C, Hornemann T, Yiannikas C. Hereditary sensory and autonomic neuropathy type IC accompanied by upper motor neuron abnormalities and type II juxtafoveal retinal telangiectasias. J Peripher Nerv Syst 2019; 24:224-229. [PMID: 30866134 DOI: 10.1111/jns.12315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 03/02/2019] [Accepted: 03/08/2019] [Indexed: 11/28/2022]
Abstract
Hereditary sensory and autonomic neuropathy type I (HSAN-1) is an autosomal dominant sensory neuropathy occurring secondary to mutations in the SPTLC1 and SPTLC2 genes. We present two generations of a single family with Ser384Phe mutation in the SPTLC2 gene located on chromosome 14q24 characterized by a typical HSAN-1c presentation, with additional findings upper motor neuron signs, early demyelinating features on nerve conduction studies, and type II juxtafoveal retinal telangiectasias also known as macular telangiectasias (MacTel II). Although HSAN1 is characterized as an axonal neuropathy, demyelinating features were identified in two subjects on serial nerve conduction studies comprising motor conduction block, temporal dispersion, and prolongation of F-waves. MacTell II is a rare syndrome characterized by bilateral macular depigmentation and Müller cell loss. It has a presumed genetic basis, and these cases suggest that the accumulation of toxic sphingoplipids may lead to Müller cell degeneration, subsequent neuronal loss, depigmentation, and progressive central macular thinning.
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Affiliation(s)
- James Triplett
- Department of Neurology, Concord Repatriation General Hospital, Sydney, New South Wales, Australia
| | - Garth Nicholson
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney, New South Wales, Australia.,Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.,Molecular Medicine, Concord Repatriation General Hospital, Sydney, New South Wales, Australia
| | - Carolyn Sue
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.,Department of Neurogenetics, Kolling Institute, Royal North Shore Hospital, Sydney, New South Wales, Australia.,Kinghorn Centre for Clinical Genomics, Garvan Institute, Sydney, New South Wales, Australia
| | - Thorsten Hornemann
- Institute for Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Con Yiannikas
- Department of Neurology, Concord Repatriation General Hospital, Sydney, New South Wales, Australia.,Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
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58
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Lone MA, Santos T, Alecu I, Silva LC, Hornemann T. 1-Deoxysphingolipids. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:512-521. [PMID: 30625374 DOI: 10.1016/j.bbalip.2018.12.013] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 12/14/2022]
Abstract
Sphingolipids (SLs) are fundamental components of eukaryotic cells. 1-Deoxysphingolipids differ structurally from canonical SLs as they lack the essential C1-OH group. Consequently, 1-deoxysphingolipids cannot be converted to complex sphingolipids and are not degraded over the canonical catabolic pathways. Pathologically elevated 1-deoxySLs are involved in several disease conditions. Within this review, we will provide an up-to-date overview on the metabolic, physiological and pathophysiological aspects of this enigmatic class of "headless" sphingolipids.
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Affiliation(s)
- M A Lone
- Institute for Clinical Chemistry, University Hospital Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland
| | - T Santos
- Institute for Clinical Chemistry, University Hospital Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland; iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - I Alecu
- Neural Regeneration Laboratory, India Taylor Lipidomic Research Platform, Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, Ottawa Brain and Mind Research Institute, University of Ottawa, Canada
| | - L C Silva
- iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - T Hornemann
- Institute for Clinical Chemistry, University Hospital Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland.
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59
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Harrison PJ, Dunn T, Campopiano DJ. Sphingolipid biosynthesis in man and microbes. Nat Prod Rep 2018; 35:921-954. [PMID: 29863195 PMCID: PMC6148460 DOI: 10.1039/c8np00019k] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Indexed: 12/20/2022]
Abstract
A new review covering up to 2018 Sphingolipids are essential molecules that, despite their long history, are still stimulating interest today. The reasons for this are that, as well as playing structural roles within cell membranes, they have also been shown to perform a myriad of cell signalling functions vital to the correct function of eukaryotic and prokaryotic organisms. Indeed, sphingolipid disregulation that alters the tightly-controlled balance of these key lipids has been closely linked to a number of diseases such as diabetes, asthma and various neuropathologies. Sphingolipid biogenesis, metabolism and regulation is mediated by a large number of enzymes, proteins and second messengers. There appears to be a core pathway common to all sphingolipid-producing organisms but recent studies have begun to dissect out important, species-specific differences. Many of these have only recently been discovered and in most cases the molecular and biochemical details are only beginning to emerge. Where there is a direct link from classic biochemistry to clinical symptoms, a number a drug companies have undertaken a medicinal chemistry campaign to try to deliver a therapeutic intervention to alleviate a number of diseases. Where appropriate, we highlight targets where natural products have been exploited as useful tools. Taking all these aspects into account this review covers the structural, mechanistic and regulatory features of sphingolipid biosynthetic and metabolic enzymes.
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Affiliation(s)
- Peter J. Harrison
- School of Chemistry
, University of Edinburgh
,
David Brewster Road
, Edinburgh
, EH9 3FJ
, UK
.
| | - Teresa M. Dunn
- Department of Biochemistry and Molecular Biology
, Uniformed Services University
,
Bethesda
, Maryland
20814
, USA
| | - Dominic J. Campopiano
- School of Chemistry
, University of Edinburgh
,
David Brewster Road
, Edinburgh
, EH9 3FJ
, UK
.
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60
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Identification of progesterone receptor membrane component-1 as an interaction partner and possible regulator of fatty acid 2-hydroxylase. Biochem J 2018; 475:853-871. [PMID: 29438993 DOI: 10.1042/bcj20170963] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/02/2018] [Accepted: 02/08/2018] [Indexed: 12/20/2022]
Abstract
The fatty acid 2-hydroxylase (FA2H) is essential for synthesis of 2-hydroxylated fatty acids in myelinating and other cells, and deficiency of this enzyme causes a complicated form of hereditary spastic paraplegia also known as fatty acid hydroxylase-associated neurodegeneration. Despite its important role in sphingolipid metabolism, regulation of FA2H and its interaction with other proteins involved in the same or other metabolic pathways is poorly understood. To identify potential interaction partners of the enzyme, quantitative mass spectrometry using stable isotope labeling of cells was combined with formaldehyde cross-linking and proximity biotinylation, respectively. Besides other enzymes involved in sphingolipid synthesis and intermembrane transfer of ceramide, and putative redox partners of FA2H, progesterone receptor membrane component-1 (PGRMC1) and PGRMC2 were identified as putative interaction partners. These two related heme-binding proteins are known to regulate several cytochrome P450 enzymes. Bimolecular fluorescence complementation experiments confirmed the interaction of FA2H with PGRMC1. Moreover, the PGRMC1 inhibitor AG-205 significantly reduced synthesis of hydroxylated ceramide and glucosylceramide in FA2H-expressing cells. This suggests that PGRMC1 may regulate FA2H activity, possibly through its heme chaperone activity.
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61
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Li Z, Kabir I, Tietelman G, Huan C, Fan J, Worgall T, Jiang XC. Sphingolipid de novo biosynthesis is essential for intestine cell survival and barrier function. Cell Death Dis 2018; 9:173. [PMID: 29415989 PMCID: PMC5833386 DOI: 10.1038/s41419-017-0214-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 11/13/2017] [Accepted: 12/07/2017] [Indexed: 12/15/2022]
Abstract
Serine palmitoyltransferase (SPT) is the rate-limiting enzyme for sphingolipid biosynthesis. SPT has two major subunits, SPTLC1 and SPTLC2. We previously found that liver Sptlc2 deficiency in early life impairs the development of adherens junctions. Here, we investigated the role of Sptlc2 deficiency in intestine. We treated Sptlc2-Flox/villin-Cre-ERT2 mice with tamoxifen (days 1, 2, and 3) to ablate Sptlc2 specifically in the intestine. At day 6 after tamoxifen treatment, Sptlc2-deficient mice had significantly decreased body weight with concurrent diarrhea and rectal bleeding. The number of goblet cells was reduced in both large and small intestine of Sptlc2-deficient mice compared with controls. Sptlc2 deficiency suppressed the level of mucin2 in the colon and increased circulating lipopolysaccharides, suggesting that SPT activity has a housekeeping function in the intestine. All Sptlc2-deficient mice died 7-10 days after tamoxifen treatment. Notably, supplementation with antibiotics and dexamethasone reduced lethality by 70%. We also found that colon specimens from patients with inflammatory bowel diseases had significantly reduced Sptlc2 expression, SPTLC2 staining, and goblet cell numbers. SPT activity is crucial for intestinal cell survival and barrier function.
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Affiliation(s)
- Zhiqiang Li
- Department of Cell Biology, State University of New York, Downstate Medical Center, Brooklyn, NY, 11203, USA
- Molecular and Cellular Cardiology Program, VA New York Harbor Healthcare System, Brooklyn, NY, 11209, USA
| | - Inamul Kabir
- Department of Cell Biology, State University of New York, Downstate Medical Center, Brooklyn, NY, 11203, USA
| | - Gladys Tietelman
- Department of Cell Biology, State University of New York, Downstate Medical Center, Brooklyn, NY, 11203, USA
| | - Chongmin Huan
- Department of Cell Biology, State University of New York, Downstate Medical Center, Brooklyn, NY, 11203, USA
| | - Jianglin Fan
- Department of Molecular Pathology, University of Yamanashi, Yamanashi, Japan
| | - Tilla Worgall
- Department of Medicine, Columbia University, New York, NY, 10032, USA
| | - Xian-Cheng Jiang
- Department of Cell Biology, State University of New York, Downstate Medical Center, Brooklyn, NY, 11203, USA.
- Molecular and Cellular Cardiology Program, VA New York Harbor Healthcare System, Brooklyn, NY, 11209, USA.
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62
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Auranen M, Toppila J, Suriyanarayanan S, Lone MA, Paetau A, Tyynismaa H, Hornemann T, Ylikallio E. Clinical and metabolic consequences of L-serine supplementation in hereditary sensory and autonomic neuropathy type 1C. Cold Spring Harb Mol Case Stud 2017; 3:mcs.a002212. [PMID: 29042446 PMCID: PMC5701299 DOI: 10.1101/mcs.a002212] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 09/05/2017] [Indexed: 12/14/2022] Open
Abstract
Hereditary sensory neuropathy type 1 (HSAN1) may be the first genetic neuropathy amenable to a specific mechanism-based treatment, as L-serine supplementation can be used to lower the neurotoxic levels of 1-deoxysphingolipids (1-deoxySL) that cause the neurodegeneration. The treatment is so far untested in HSAN1C caused by variants in the serine palmitoyl transferase subunit 2 (SPTLC2) gene. The aim of this study was to establish whether oral L-serine lowers 1-deoxySL in a patient with HSAN1C, to perform a dose escalation to find the minimal effective dose, and to assess the safety profile and global metabolic effects of the treatment. Our patient underwent a 52-wk treatment in which the L-serine dose was titrated up to 400 mg/kg/day. She was followed up by repeated clinical examination, nerve conduction testing, and skin biopsies to document effects on small nerve fibers. Serum was assayed for 1-deoxySL and metabolomics analysis of 111 metabolites. We found a robust lowering of 1-deoxySL, which correlated in a near-linear fashion with increased serum L-serine levels. Metabolomics analysis showed a modest elevation in glycine and a marked reduction in the level of cytosine, whereas most of the other assayed metabolites did not change. There were no direct side effects from the treatment, but the patient developed a transitory toe ulceration during the course of the study. The Charcot–Marie–Tooth neuropathy score increased by 1 point. We conclude that oral supplementation of L-serine decreases 1-deoxySL in HSAN1C without major global effects on metabolism. L-serine is therefore a potential treatment for HSAN1C.
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Affiliation(s)
- Mari Auranen
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki 00014, Finland.,Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki 00029, Finland
| | - Jussi Toppila
- Department of Clinical Neurophysiology, Medical Imaging Center, Helsinki University Hospital, Helsinki 00029, Finland
| | - Saranya Suriyanarayanan
- Institute for Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich 8091, Switzerland.,Competence Center for Personalized Medicine (CC-PM), Zurich 8044, Switzerland
| | - Museer A Lone
- Institute for Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich 8091, Switzerland.,Competence Center for Personalized Medicine (CC-PM), Zurich 8044, Switzerland
| | - Anders Paetau
- Department of Pathology, HUSLAB and University of Helsinki, Helsinki 00029, Finland
| | - Henna Tyynismaa
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki 00014, Finland
| | - Thorsten Hornemann
- Institute for Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich 8091, Switzerland.,Competence Center for Personalized Medicine (CC-PM), Zurich 8044, Switzerland
| | - Emil Ylikallio
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki 00014, Finland.,Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki 00029, Finland
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63
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Karandashova S, Kummarapurugu AB, Zheng S, Chalfant CE, Voynow JA. Neutrophil elastase increases airway ceramide levels via upregulation of serine palmitoyltransferase. Am J Physiol Lung Cell Mol Physiol 2017; 314:L206-L214. [PMID: 29025713 DOI: 10.1152/ajplung.00322.2017] [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: 01/20/2023] Open
Abstract
Altered sphingolipid metabolism is associated with increased inflammation; however, the impact of inflammatory mediators, including neutrophil elastase (NE), on airway sphingolipid homeostasis remains unknown. Using a well-characterized mouse model of NE oropharyngeal aspiration, we investigated a potential link between NE-induced airway inflammation and increased synthesis of various classes of sphingolipids, including ceramide species. Sphingolipids in bronchoalveolar lavage fluids (BAL) were identified and quantified using reverse-phase high-performance liquid chromatography/electrospray ionization tandem mass spectrometry analysis. BAL total and differential cell counts, CXCL1/keratinocyte chemoattractant (KC) protein levels, and high-mobility group box 1 (HMGB1) protein levels were determined. NE exposure increased BAL long-chain ceramides, total cell and neutrophil counts, and upregulated KC and HMGB1. The mRNA and protein levels of serine palmitoyltransferase (SPT) long-chain subunits 1 and 2, the multimeric enzyme responsible for the first, rate-limiting step of de novo ceramide generation, were determined by qRT-PCR and Western analyses, respectively. NE increased lung SPT long-chain subunit 2 (SPTLC2) protein levels but not SPTLC1 and had no effect on mRNA for either subunit. To assess whether de novo ceramide synthesis was required for NE-induced inflammation, myriocin, a SPT inhibitor, or a vehicle control was administered intraperitoneally 2 h before NE administration. Myriocin decreased BAL d18:1/22:0 and d18:1/24:1 ceramide, KC, and HMGB1 induced by NE exposure. These results support a feed-forward cycle of NE-generated ceramide and ceramide-driven cytokine signaling that may be a potential target for intervention in lung disease typified by chronic neutrophilic inflammation.
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Affiliation(s)
- Sophia Karandashova
- Center for Clinical and Translational Research, Virginia Commonwealth University , Richmond, Virginia
| | - Apparao B Kummarapurugu
- Division of Pediatric Pulmonary Medicine, Children's Hospital of Richmond at Virginia Commonwealth University , Richmond, Virginia
| | - Shuo Zheng
- Division of Pediatric Pulmonary Medicine, Children's Hospital of Richmond at Virginia Commonwealth University , Richmond, Virginia
| | - Charles E Chalfant
- Dept. of Biochemistry and Molecular Biology, Institute of Molecular Medicine, Johnson Center for Critical Care and Pulmonary Research, and Massey Cancer Center, Virginia Commonwealth University , Richmond, Virginia.,Research Service, Hunter Holmes McGuire Veterans Administration Medical Center , Richmond, Virginia
| | - Judith A Voynow
- Division of Pediatric Pulmonary Medicine, Children's Hospital of Richmond at Virginia Commonwealth University , Richmond, Virginia
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64
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Ding NZ, Qi QR, Gu XW, Zuo RJ, Liu J, Yang ZM. De novo synthesis of sphingolipids is essential for decidualization in mice. Theriogenology 2017; 106:227-236. [PMID: 29096270 DOI: 10.1016/j.theriogenology.2017.09.036] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 06/10/2017] [Accepted: 09/30/2017] [Indexed: 12/31/2022]
Abstract
Sphingolipids play multiple roles in membrane structure, signal transduction, stress responses, neural development and immune reaction. The rate of de novo synthesis pathway of sphingolipids is regulated by two key enzymes, serine palmitoyltransferase (SPT), and ketoreductase (Kds). Here, we find that the mRNA levels of three subunits of the SPT holoenzyme (Sptlc1, Sptlc2, and Ssspta) are significantly up-regulated in mouse uterine stromal cells during decidualization. The expression of Kds, which reduces 3-keto-dihydrosphingosine to dihydrosphingosine, is co-localized with Sptlc1 in mouse uteri during early pregnancy. Moreover, l-Cycloserine, a specific inhibitor of SPT, can significantly decrease the weight and number of implantation sites, and impede the decidualization process in mouse uterine stromal cells, suggesting that blockage of de novo sphingolipid synthesis may cause defective decidualization and early pregnancy loss in mice. In addition, this study also shows progesterone (P4) can stimulate the expression of both Sptlc2 and Ssspta in mouse uterus. Therefore, our study shows that de novo synthesis of sphingolipids is necessary in implantation and plays a key role in decidualization of mouse.
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Affiliation(s)
- Nai-Zheng Ding
- Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Science, Shandong Normal University, Jinan 250014, China.
| | - Qian-Rong Qi
- Department of Biology, Shantou University, Shantou 515063, China
| | - Xiao-Wei Gu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
| | - Ru-Juan Zuo
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
| | - Jie Liu
- Department of Biology, Shantou University, Shantou 515063, China
| | - Zeng-Ming Yang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China.
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65
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The Role of Lipid Bodies in the Microglial Aging Process and Related Diseases. Neurochem Res 2017; 42:3140-3148. [PMID: 28699057 DOI: 10.1007/s11064-017-2351-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 02/22/2017] [Accepted: 07/07/2017] [Indexed: 01/08/2023]
Abstract
Lipid bodies (LBs) have long been considered to be organelles merely for the storage of neutral lipids. However, recent studies have shown the significance of LBs in signal transduction, especially in glial cells, including microglia. Microglial cells are the resident mononuclear phagocytes in the central nervous system and have a close relationship with the aging process and neurodegenerative diseases. Evidence suggests that LBs accumulate and are remodeled during the aging process and the development of neuroinflammatory conditions. However, the mechanisms underlying the formation of LBs under these conditions and the mechanism by which LB remodeling influences the progression of neurodegeneration remain to be clarified. In this review, we have summarized the findings from recent studies with the aim of further elucidating these issues.
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66
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Zhang QH, Yin RX, Gao H, Huang F, Wu JZ, Pan SL, Lin WX, Yang DZ. Association of the SPTLC3 rs364585 polymorphism and serum lipid profiles in two Chinese ethnic groups. Lipids Health Dis 2017; 16:1. [PMID: 28056980 PMCID: PMC5217591 DOI: 10.1186/s12944-016-0392-3] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 12/14/2016] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Little is known about the association of the single nucleotide polymorphism (SNP) of rs364585 near serine palmitoyl-transferase long-chain base subunit 3 gene (SPTLC3) and serum lipid profiles. The present study was detected the association of the SPTLC3 rs364585 SNP and several environmental factors with serum lipid profiles in the Han and Jing populations. METHODS Genotyping of the SPTLC3 rs364585 SNP was performed in 824 unrelated individuals of Han and 783 participants of Jing by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing. RESULTS There was no significant difference in either genotypic or allelic frequencies between Han and Jing, or between males and females of the both ethnic groups. The levels of serum low-density lipoprotein cholesterol (LDL-C) and the ratio of apolipoprotein (Apo) A1 to ApoB in Han; and total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and LDL-C in Jing were different between the A allele carriers and the A allele non-carriers (P < 0.05-0.001). Subgroup analysis according to sex showed that the levels of LDL-C in Han males; TC and LDL-C in Jing males; and HDL-C and LDL-C in Jing females were different between the A allele carriers and the A allele non-carriers (P < 0.05-0.001), the A allele carriers had higher LDL-C and TC levels, and lower HDL-C levels than the A allele non-carriers. Serum lipid traits were also associated with several environmental factors in the Han and Jing populations, or in males and females of the both ethnic groups. CONCLUSIONS The present study demonstrates the association between the SPTLC3 rs364585 SNP and serum TC, HDL-C and LDL-C levels in our study populations. These associations might have ethnic- and/or sex-specificity. TRIAL REGISTRATION Retrospectively registered.
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Affiliation(s)
- Qing-Hui Zhang
- Department of Cardiology, Institute of Cardiovascular Diseases, The First Affiliated Hospital, Guangxi Medical University, 22 Shuangyong Road, Nanning, Guangxi, 530021, People's Republic of China
| | - Rui-Xing Yin
- Department of Cardiology, Institute of Cardiovascular Diseases, The First Affiliated Hospital, Guangxi Medical University, 22 Shuangyong Road, Nanning, Guangxi, 530021, People's Republic of China.
| | - Hui Gao
- Department of Cardiology, Institute of Cardiovascular Diseases, The First Affiliated Hospital, Guangxi Medical University, 22 Shuangyong Road, Nanning, Guangxi, 530021, People's Republic of China
| | - Feng Huang
- Department of Cardiology, Institute of Cardiovascular Diseases, The First Affiliated Hospital, Guangxi Medical University, 22 Shuangyong Road, Nanning, Guangxi, 530021, People's Republic of China
| | - Jin-Zhen Wu
- Department of Cardiology, Institute of Cardiovascular Diseases, The First Affiliated Hospital, Guangxi Medical University, 22 Shuangyong Road, Nanning, Guangxi, 530021, People's Republic of China
| | - Shang-Ling Pan
- Department of Pathophysiology, School of Premedical Sciences, Guangxi Medical University, Nanning, Guangxi, 530021, People's Republic of China
| | - Wei-Xiong Lin
- Department of Molecular Biology, Medical Scientific Research Center, Guangxi Medical University, Nanning, Guangxi, 530021, People's Republic of China
| | - De-Zhai Yang
- Department of Molecular Biology, Medical Scientific Research Center, Guangxi Medical University, Nanning, Guangxi, 530021, People's Republic of China
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67
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Pharmacological characterization of synthetic serine palmitoyltransferase inhibitors by biochemical and cellular analyses. Biochem Biophys Res Commun 2016; 497:1171-1176. [PMID: 28042036 DOI: 10.1016/j.bbrc.2016.12.182] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 12/28/2016] [Indexed: 12/11/2022]
Abstract
Human serine palmitoyltransferase (SPT) is a PLP-dependent enzyme residing in the endoplasmic reticulum. It catalyzes the synthesis of 3-ketodihydrosphingosine (3-KDS) from the substrates palmitoyl-CoA and l-serine. It is a rate-limiting enzyme for sphingolipid synthesis in cells. In the present study, we characterized and pharmacologically profiled a series of tetrahydropyrazolopyridine derivatives that potently inhibit human SPT enzymatic activity, including two cell-active derivatives and one fluorescent-labelled derivative. These SPT inhibitors exhibited dual inhibitory activities against SPT2 and SPT3. We used a fluorescent-labelled probe to molecularly assess the inhibitory mechanism and revealed its binding to the SPT2 or SPT3 subunit in the small subunit (ss) SPTa/SPT1/SPT2/or ssSPTa/SPT1/SPT3 functional complexes. One of the SPT inhibitors exhibited a significantly slow dissociation from the SPT complex. We confirmed that our SPT inhibitors suppressed ceramide content in non-small-cell lung cancer cell line, HCC4006, by performing a target engagement analysis. The potency of ceramide reduction correlated to that observed in a recombinant SPT2 enzyme assay. We thus elucidated and provided a fundamental understanding of the molecular mode of action of SPT inhibitors and developed potent, cell-active SPT inhibitors that can be used to clarify the biological function of SPT.
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68
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Li Z, Kabir I, Jiang H, Zhou H, Libien J, Zeng J, Stanek A, Ou P, Li KR, Zhang S, Bui HH, Kuo MS, Park TS, Kim B, Worgall TS, Huan C, Jiang XC. Liver serine palmitoyltransferase activity deficiency in early life impairs adherens junctions and promotes tumorigenesis. Hepatology 2016; 64:2089-2102. [PMID: 27642075 PMCID: PMC5115983 DOI: 10.1002/hep.28845] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 08/18/2016] [Accepted: 09/08/2016] [Indexed: 12/22/2022]
Abstract
UNLABELLED Serine palmitoyltransferase is the key enzyme in sphingolipid biosynthesis. Mice lacking serine palmitoyltransferase are embryonic lethal. We prepared liver-specific mice deficient in the serine palmitoyltransferase long chain base subunit 2 gene using an albumin-cyclization recombination approach and found that the deficient mice have severe jaundice. Moreover, the deficiency impairs hepatocyte polarity, attenuates liver regeneration after hepatectomy, and promotes tumorigenesis. Importantly, we show that the deficiency significantly reduces sphingomyelin but not other sphingolipids in hepatocyte plasma membrane; greatly reduces cadherin, the major protein in adherens junctions, on the membrane; and greatly induces cadherin phosphorylation, an indication of its degradation. The deficiency affects cellular distribution of β-catenin, the central component of the canonical Wnt pathway. Furthermore, such a defect can be partially corrected by sphingomyelin supplementation in vivo and in vitro. CONCLUSION The plasma membrane sphingomyelin level is one of the key factors in regulating hepatocyte polarity and tumorigenesis. (Hepatology 2016;64:2089-2102).
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Affiliation(s)
- Zhiqiang Li
- Department of Cell Biology, Department of Surgery, and Department of Pathology, SUNY Downstate Medical Center,Molecular and Cellular Cardiology Program, VA New York Harbor Healthcare System, Brooklyn
| | - Inamul Kabir
- Department of Cell Biology, Department of Surgery, and Department of Pathology, SUNY Downstate Medical Center
| | - Hui Jiang
- Department of Cell Biology, Department of Surgery, and Department of Pathology, SUNY Downstate Medical Center
| | | | - Jenny Libien
- Department of Cell Biology, Department of Surgery, and Department of Pathology, SUNY Downstate Medical Center
| | - Jianying Zeng
- Department of Cell Biology, Department of Surgery, and Department of Pathology, SUNY Downstate Medical Center
| | - Albert Stanek
- Department of Cell Biology, Department of Surgery, and Department of Pathology, SUNY Downstate Medical Center
| | - Peiqi Ou
- Department of Cell Biology, Department of Surgery, and Department of Pathology, SUNY Downstate Medical Center
| | - Kailyn R. Li
- Department of Cell Biology, Department of Surgery, and Department of Pathology, SUNY Downstate Medical Center
| | - Shane Zhang
- Department of Cell Biology, Department of Surgery, and Department of Pathology, SUNY Downstate Medical Center
| | - Hai H. Bui
- Lilly Research Laboratories, Eli Lilly & Company, Indianapolis, IN, 46285
| | - Ming-Shang Kuo
- Lilly Research Laboratories, Eli Lilly & Company, Indianapolis, IN, 46285
| | - Tae-Sik Park
- Department of Life Science, Gachon University, Sungnam, South Korea
| | | | | | - Chongmin Huan
- Department of Cell Biology, Department of Surgery, and Department of Pathology, SUNY Downstate Medical Center,Correspondence: ; Or
| | - Xian-Cheng Jiang
- Department of Cell Biology, Department of Surgery, and Department of Pathology, SUNY Downstate Medical Center,Molecular and Cellular Cardiology Program, VA New York Harbor Healthcare System, Brooklyn,Correspondence: ; Or
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69
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Maekawa M, Lee M, Wei K, Ridgway ND, Fairn GD. Staurosporines decrease ORMDL proteins and enhance sphingomyelin synthesis resulting in depletion of plasmalemmal phosphatidylserine. Sci Rep 2016; 6:35762. [PMID: 27805006 PMCID: PMC5090970 DOI: 10.1038/srep35762] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 10/05/2016] [Indexed: 12/03/2022] Open
Abstract
Accumulation of phosphatidylserine in the inner leaflet of the plasma membrane is a hallmark of eukaryotes. Sublethal levels of staurosporine and related compounds deplete phosphatidylserine from the plasma membrane and abrogate K-Ras signaling. Here, we report that low-dose staurosporine and related compounds increase sphingomyelin mass. Mass-spectrometry and metabolic tracer analysis revealed an increase in both the levels and rate of synthesis of sphingomyelin in response to sublethal staurosporine. Mechanistically, it was determined that the abundance of the ORMDL proteins, which negatively regulate serine-palmitoyltransferase, are decreased by low-dose staurosporine. Finally, inhibition of ceramide synthesis, and thus sphingomyelin, prevented the displacement of phosphatidylserine and cholesterol from the inner leaflet of the plasma membrane. The results establish that an optimal level of sphingomyelin is required to maintain the distribution of phosphatidylserine and cholesterol in the plasma membrane and further demonstrate a complex relationship between the trafficking of phosphatidylserine and sphingomyelin.
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Affiliation(s)
- Masashi Maekawa
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON, Canada
| | - Minhyoung Lee
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Kuiru Wei
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON, Canada
| | - Neale D Ridgway
- Departments of Pediatrics, and Biochemistry &Molecular Biology, Atlantic Research Centre, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Gregory D Fairn
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Department of Surgery, University of Toronto, Toronto, ON, Canada
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70
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Sasset L, Zhang Y, Dunn TM, Di Lorenzo A. Sphingolipid De Novo Biosynthesis: A Rheostat of Cardiovascular Homeostasis. Trends Endocrinol Metab 2016; 27:807-819. [PMID: 27562337 PMCID: PMC5075255 DOI: 10.1016/j.tem.2016.07.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/07/2016] [Accepted: 07/20/2016] [Indexed: 01/01/2023]
Abstract
Sphingolipids (SL) are both fundamental structural components of the eukaryotic membranes and signaling molecules that regulate a variety of biological functions. The highly-bioactive lipids, ceramide and sphingosine-1-phosphate, have emerged as important regulators of cardiovascular function in health and disease. In this review we discuss recent insights into the role of SLs, particularly ceramide and sphingosine-1-phosphate, in the pathophysiology of the cardiovascular system. We also highlight advances into the molecular mechanisms regulating serine palmitoyltransferase, the first and rate-limiting enzyme of de novo SL biosynthesis, with an emphasis on the recently discovered inhibitors of serine palmitoyltransferase, ORMDL and NOGO-B proteins. Understanding the molecular mechanisms regulating this biosynthetic pathway may lead to the development of novel therapeutic approaches for the treatment of cardiovascular diseases.
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Affiliation(s)
- Linda Sasset
- Center for Vascular Biology, Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, Cornell University, New York, NY 10065, USA
| | - Yi Zhang
- Center for Vascular Biology, Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, Cornell University, New York, NY 10065, USA
| | - Teresa M Dunn
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Annarita Di Lorenzo
- Center for Vascular Biology, Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, Cornell University, New York, NY 10065, USA.
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71
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Hernández-Corbacho MJ, Salama MF, Canals D, Senkal CE, Obeid LM. Sphingolipids in mitochondria. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:56-68. [PMID: 27697478 DOI: 10.1016/j.bbalip.2016.09.019] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 08/01/2016] [Accepted: 09/24/2016] [Indexed: 01/16/2023]
Abstract
Sphingolipids are bioactive lipids found in cell membranes that exert a critical role in signal transduction. In recent years, it has become apparent that sphingolipids participate in growth, senescence, differentiation and apoptosis. The anabolism and catabolism of sphingolipids occur in discrete subcellular locations and consist of a strictly regulated and interconnected network, with ceramide as the central hub. Altered sphingolipid metabolism is linked to several human diseases. Hence, an advanced knowledge of how and where sphingolipids are metabolized is of paramount importance in order to understand the role of sphingolipids in cellular functions. In this review, we provide an overview of sphingolipid metabolism. We focus on the distinct pathways of ceramide synthesis, highlighting the mitochondrial ceramide generation, transport of ceramide to mitochondria and its role in the regulation of mitochondrial-mediated apoptosis, mitophagy and implications to disease. We will discuss unanswered questions and exciting future directions. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum.
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Affiliation(s)
- María José Hernández-Corbacho
- Stony Brook Cancer Center and the Department of Medicine, Stony Brook University, Health Sciences Center, Stony Brook, NY 11794, USA
| | - Mohamed F Salama
- Stony Brook Cancer Center and the Department of Medicine, Stony Brook University, Health Sciences Center, Stony Brook, NY 11794, USA; Department of Biochemistry, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Daniel Canals
- Stony Brook Cancer Center and the Department of Medicine, Stony Brook University, Health Sciences Center, Stony Brook, NY 11794, USA
| | - Can E Senkal
- Stony Brook Cancer Center and the Department of Medicine, Stony Brook University, Health Sciences Center, Stony Brook, NY 11794, USA
| | - Lina M Obeid
- Stony Brook Cancer Center and the Department of Medicine, Stony Brook University, Health Sciences Center, Stony Brook, NY 11794, USA; The Northport VA Medical Center, Northport, NY 11768, USA.
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72
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Kihara A. Synthesis and degradation pathways, functions, and pathology of ceramides and epidermal acylceramides. Prog Lipid Res 2016; 63:50-69. [PMID: 27107674 DOI: 10.1016/j.plipres.2016.04.001] [Citation(s) in RCA: 145] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 04/08/2016] [Accepted: 04/20/2016] [Indexed: 10/21/2022]
Abstract
Ceramide (Cer) is a structural backbone of sphingolipids and is composed of a long-chain base and a fatty acid. Existence of a variety of Cer species, which differ in chain-length, hydroxylation status, and/or double bond number of either of their hydrophobic chains, has been reported. Ceramide is produced by Cer synthases. Mammals have six Cer synthases (CERS1-6), each of which exhibits characteristic substrate specificity toward acyl-CoAs with different chain-lengths. Knockout mice for each Cer synthase show corresponding, isozyme-specific phenotypes, revealing the functional differences of Cers with different chain-lengths. Cer diversity is especially prominent in epidermis. Changes in Cer levels, composition, and chain-lengths are associated with atopic dermatitis. Acylceramide (acyl-Cer) specifically exists in epidermis and plays an essential role in skin permeability barrier formation. Accordingly, defects in acyl-Cer synthesis cause the cutaneous disorder ichthyosis with accompanying severe skin barrier defects. Although the molecular mechanism by which acyl-Cer is generated was long unclear, most genes involved in its synthesis have been identified recently. In Cer degradation pathways, the long-chain base moiety of Cer is converted to acyl-CoA, which is then incorporated mainly into glycerophospholipids. This pathway generates the lipid mediator sphingosine 1-phosphate. This review will focus on recent advances in our understanding of the synthesis and degradation pathways, physiological functions, and pathology of Cers/acyl-Cers.
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Affiliation(s)
- Akio Kihara
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12-jo, Nishi 6-choume, Kita-ku, Sapporo 060-0812, Japan.
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73
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Inhibition of ceramide de novo synthesis by myriocin produces the double effect of reducing pathological inflammation and exerting antifungal activity against A. fumigatus airways infection. Biochim Biophys Acta Gen Subj 2016; 1860:1089-97. [PMID: 26922830 DOI: 10.1016/j.bbagen.2016.02.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 02/02/2016] [Accepted: 02/22/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND Fungal infections develop in pulmonary chronic inflammatory diseases such as asthma, Chronic Obstructive Pulmonary Disease (COPD) and Cystic Fibrosis (CF). The available antifungal drugs may fail to eradicate fungal pathogens, that can invade the lungs and vessels and spread by systemic circulation taking advantage of defective lung immunity. An increased rate of sphingolipid de novo synthesis, leading to ceramide accumulation, was demonstrated in CF and COPD inflamed lungs. The inhibitor of sphingolipid synthesis myriocin reduces inflammation and ameliorates the response against bacterial airway infection in CF mice. Myriocin also inhibits sphingolipid synthesis in fungi and exerts a powerful fungistatic effect. METHODS We treated Aspergillus fumigatus infected airway epithelial cells with myriocin and we administered myriocin-loaded nanocarriers to A. fumigatus infected mice lung. RESULTS We demonstrate here that de novo synthesized ceramide mediates the inflammatory response induced by A. fumigatus infection in airway epithelia. CF epithelial cells are chronically inflamed and defective in killing internalized conidia. Myriocin treatment reduced ceramide increase and inflammatory mediator release whereas it upregulated HO1 and NOD2, allowing the recovery of a functional killing of conidia in these cells. Myriocin-loaded nanocarriers, intratracheally administered to mice, significantly reduced both the inflammatory response induced by A. fumigatus pulmonary challenge and fungal lung invasion. CONCLUSIONS We conclude that inhibition of sphingolipid synthesis can be envisaged as a dual anti-inflammatory and anti-fungal therapy in patients suffering from chronic lung inflammation with compromised immunity. GENERAL SIGNIFICANCE Myriocin represents a powerful agent for inflammatory diseases and fungal infection.
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Yamane T, Muramatsu A, Yoshino S, Matsui S, Shimura M, Tsujii Y, Iwatsuki K, Kobayashi-Hattori K, Oishi Y. mTOR inhibition by rapamycin increases ceramide synthesis by promoting transforming growth factor-β1/Smad signaling in the skin. FEBS Open Bio 2016; 6:317-25. [PMID: 27239444 PMCID: PMC4821357 DOI: 10.1002/2211-5463.12039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 01/27/2016] [Accepted: 01/27/2016] [Indexed: 01/10/2023] Open
Abstract
Although mammalian target of rapamycin (mTOR) mediates a wide variety of biological functions, little information is available on the effect of mTOR on the functions of skin cells. In this study, we investigated effects of mTOR inhibition by rapamycin on ceramide synthesis in the skin of rats and human keratinocytes and its regulatory mechanisms. The phosphorylation of p70 S6 kinase, which indicates mTOR activation, was induced in the skin of rats fed a high-fat diet, but this abnormality was reversed by supplementation with rapamycin. Ceramide levels and the mRNA levels of serine palmitoyltransferase (SPT) and transforming growth factor (TGF)-β1 were suppressed in the skin of rats fed high-fat diets, but this abnormality was reversed by supplementation with rapamycin. TGF-β1-induced SPT mRNA expression was blocked by SB525334, an inhibitor of TGF-β1-induced Smad2/3 nuclear localization, in human keratinocytes. Rapamycin-induced SPT mRNA expression was blocked by an anti-TGF-β1 antibody or SB525334 in human keratinocytes. These results show that mTOR inhibition by rapamycin increases ceramide synthesis by promoting TGF-β1/Smad signaling in the skin.
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Affiliation(s)
- Takumi Yamane
- Department of Nutritional Science and Food Safety Faculty of Applied Bioscience Tokyo University of Agriculture Setagaya-ku Japan
| | - Aimi Muramatsu
- Department of Nutritional Science Faculty of Applied Bioscience Tokyo University of Agriculture Setagaya-ku Japan
| | - Sawako Yoshino
- Department of Nutritional Science and Food Safety Faculty of Applied Bioscience Tokyo University of Agriculture Setagaya-ku Japan
| | - Sho Matsui
- Department of Nutritional Science Faculty of Applied Bioscience Tokyo University of Agriculture Setagaya-ku Japan
| | - Mari Shimura
- Department of Nutritional Science and Food Safety Faculty of Applied Bioscience Tokyo University of Agriculture Setagaya-ku Japan
| | - Yoshimasa Tsujii
- Department of Applied Biology and Chemistry Faculty of Applied Bioscience Tokyo University of Agriculture Setagaya-ku Japan
| | - Ken Iwatsuki
- Department of Nutritional Science and Food Safety Faculty of Applied Bioscience Tokyo University of Agriculture Setagaya-ku Japan
| | - Kazuo Kobayashi-Hattori
- Department of Nutritional Science Faculty of Applied Bioscience Tokyo University of Agriculture Setagaya-ku Japan
| | - Yuichi Oishi
- Department of Nutritional Science and Food Safety Faculty of Applied Bioscience Tokyo University of Agriculture Setagaya-ku Japan
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75
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Bode H, Bourquin F, Suriyanarayanan S, Wei Y, Alecu I, Othman A, Von Eckardstein A, Hornemann T. HSAN1 mutations in serine palmitoyltransferase reveal a close structure-function-phenotype relationship. Hum Mol Genet 2015; 25:853-65. [PMID: 26681808 DOI: 10.1093/hmg/ddv611] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 12/12/2015] [Indexed: 12/13/2022] Open
Abstract
Hereditary sensory and autonomic neuropathy type 1 (HSAN1) is a rare autosomal dominant inherited peripheral neuropathy caused by mutations in the SPTLC1 and SPTLC2 subunits of serine palmitoyltransferase (SPT). The mutations induce a permanent shift in the substrate preference from L-serine to L-alanine, which results in the pathological formation of atypical and neurotoxic 1-deoxy-sphingolipids (1-deoxySL). Here we compared the enzymatic properties of 11 SPTLC1 and six SPTLC2 mutants using a uniform isotope labelling approach. In total, eight SPT mutants (STPLC1p.C133W, p.C133Y, p.S331F, p.S331Y and SPTLC2p.A182P, p.G382V, p.S384F, p.I504F) were associated with increased 1-deoxySL synthesis. Despite earlier reports, canonical activity with l-serine was not reduced in any of the investigated SPT mutants. Three variants (SPTLC1p.S331F/Y and SPTLC2p.I505Y) showed an increased canonical activity and increased formation of C20 sphingoid bases. These three mutations are associated with an exceptionally severe HSAN1 phenotype, and increased C20 sphingosine levels were also confirmed in plasma of patients. A principal component analysis of the analysed sphingoid bases clustered the mutations into three separate entities. Each cluster was related to a distinct clinical outcome (no, mild and severe HSAN1 phenotype). A homology model based on the protein structure of the prokaryotic SPT recapitulated the same grouping on a structural level. Mutations associated with the mild form clustered around the active site, whereas mutations associated with the severe form were located on the surface of the protein. In conclusion, we showed that HSAN1 mutations in SPT have distinct biochemical properties, which allowed for the prediction of the clinical symptoms on the basis of the plasma sphingoid base profile.
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Affiliation(s)
- Heiko Bode
- Institute for Clinical Chemistry, University Hospital Zurich, Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Florence Bourquin
- Institute of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Saranya Suriyanarayanan
- Institute for Clinical Chemistry, University Hospital Zurich, Competence Center for Personalized Medicine (CC-PM), Molecular Translation and Biomedicine (MTB), and
| | - Yu Wei
- Institute for Clinical Chemistry, University Hospital Zurich
| | - Irina Alecu
- Institute for Clinical Chemistry, University Hospital Zurich, Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Alaa Othman
- Institute for Clinical Chemistry, University Hospital Zurich, Competence Center for Personalized Medicine (CC-PM), Molecular Translation and Biomedicine (MTB), and
| | - Arnold Von Eckardstein
- Institute for Clinical Chemistry, University Hospital Zurich, Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland, Competence Center for Personalized Medicine (CC-PM), Molecular Translation and Biomedicine (MTB), and
| | - Thorsten Hornemann
- Institute for Clinical Chemistry, University Hospital Zurich, Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland, Competence Center for Personalized Medicine (CC-PM), Molecular Translation and Biomedicine (MTB), and
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Fenofibrate lowers atypical sphingolipids in plasma of dyslipidemic patients: A novel approach for treating diabetic neuropathy? J Clin Lipidol 2015; 9:568-75. [DOI: 10.1016/j.jacl.2015.03.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 02/20/2015] [Accepted: 03/30/2015] [Indexed: 12/11/2022]
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77
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Metsalu T, Viltrop T, Tiirats A, Rajashekar B, Reimann E, Kõks S, Rull K, Milani L, Acharya G, Basnet P, Vilo J, Mägi R, Metspalu A, Peters M, Haller-Kikkatalo K, Salumets A. Using RNA sequencing for identifying gene imprinting and random monoallelic expression in human placenta. Epigenetics 2015; 9:1397-409. [PMID: 25437054 DOI: 10.4161/15592294.2014.970052] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Given the possible critical importance of placental gene imprinting and random monoallelic expression on fetal and infant health, most of those genes must be identified, in order to understand the risks that the baby might meet during pregnancy and after birth. Therefore, the aim of the current study was to introduce a workflow and tools for analyzing imprinted and random monoallelic gene expression in human placenta, by applying whole-transcriptome (WT) RNA sequencing of placental tissue and genotyping of coding DNA variants in family trios. Ten family trios, each with a healthy spontaneous single-term pregnancy, were recruited. Total RNA was extracted for WT analysis, providing the full sequence information for the placental transcriptome. Parental and child blood DNA genotypes were analyzed by exome SNP genotyping microarrays, mapping the inheritance and estimating the abundance of parental expressed alleles. Imprinted genes showed consistent expression from either parental allele, as demonstrated by the SNP content of sequenced transcripts, while monoallelically expressed genes had random activity of parental alleles. We revealed 4 novel possible imprinted genes (LGALS8, LGALS14, PAPPA2 and SPTLC3) and confirmed the imprinting of 4 genes (AIM1, PEG10, RHOBTB3 and ZFAT-AS1) in human placenta. The major finding was the identification of 4 genes (ABP1, BCLAF1, IFI30 and ZFAT) with random allelic bias, expressing one of the parental alleles preferentially. The main functions of the imprinted and monoallelically expressed genes included: i) mediating cellular apoptosis and tissue development; ii) regulating inflammation and immune system; iii) facilitating metabolic processes; and iv) regulating cell cycle.
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Key Words
- ASE, allele-specific expression
- FDR, false discovery rate
- GEO, Gene Expression Omnibus
- IUGR, intrauterine growth restriction
- MAF, minor allele frequency
- MHC, major histocompatibility complex
- NK cells, natural killer cells
- RNA sequencing
- RNA-Seq, RNA-sequencing
- RPKM, reads per kilobase per million
- UCSC, University of California Santa Cruz
- WT, whole-transcriptome
- allele-specific expression
- imprinting
- placenta
- random monoallelic expression
- short read mapping
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Affiliation(s)
- Tauno Metsalu
- a Institute of Computer Science ; University of Tartu ; Tartu , Estonia
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Othman A, Saely CH, Muendlein A, Vonbank A, Drexel H, von Eckardstein A, Hornemann T. Plasma C20-Sphingolipids predict cardiovascular events independently from conventional cardiovascular risk factors in patients undergoing coronary angiography. Atherosclerosis 2015; 240:216-21. [DOI: 10.1016/j.atherosclerosis.2015.03.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 03/09/2015] [Accepted: 03/09/2015] [Indexed: 12/31/2022]
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79
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ORMDL orosomucoid-like proteins are degraded by free-cholesterol-loading-induced autophagy. Proc Natl Acad Sci U S A 2015; 112:3728-33. [PMID: 25775599 DOI: 10.1073/pnas.1422455112] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Eukaryotic cells have evolved robust mechanisms to counter excess cholesterol including redistribution of lipids into different compartments and compensatory up-regulation of phospholipid biosynthesis. We demonstrate here that excess cellular cholesterol increased the activity of the endoplasmic reticulum (ER) enzyme serine palmitoyl-CoA transferase (SPT), the rate-limiting enzyme in sphingomyelin synthesis. This increased SPT activity was not due to altered levels of SPTLC1 or SPTLC2, the major subunits of SPT. Instead, cholesterol loading decreased the levels of ORMDL1, a negative regulator of SPT activity, due to its increased turnover. Several lines of evidence demonstrated that free-cholesterol-induced autophagy, which led to increased turnover of ORMDL1. Cholesterol loading induced ORMDL1 redistribution from the ER to cytoplasmic p62 positive autophagosomes. Coimmunoprecipitation analysis of cholesterol-loaded cells showed increased association between ORMDL1 and p62. The lysosomal inhibitor chloroquine or siRNA knockdown of Atg7 inhibited ORMDL1 degradation by cholesterol, whereas proteasome inhibitors showed no effect. ORMDL1 degradation was specific to free-cholesterol loading as autophagy induced by serum starvation or general ER stress did not lead to ORMDL1 degradation. ORMDL proteins are thus previously unidentified responders to excess cholesterol, exiting the ER to activate SPT and increase sphingomyelin biosynthesis, which may buffer excess cellular cholesterol.
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80
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Yoshimine Y, Uto H, Kumagai K, Mawatari S, Arima S, Ibusuki R, Mera K, Nosaki T, Kanmura S, Numata M, Tamai T, Moriuchi A, Tsubouchi H, Ido A. Hepatic expression of the Sptlc3 subunit of serine palmitoyltransferase is associated with the development of hepatocellular carcinoma in a mouse model of nonalcoholic steatohepatitis. Oncol Rep 2015; 33:1657-66. [PMID: 25607821 DOI: 10.3892/or.2015.3745] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 12/01/2014] [Indexed: 11/06/2022] Open
Abstract
The molecular mechanisms underlying the progression of nonalcoholic steatohepatitis (NASH) have not been fully elucidated. The aim of this study was to identify factors involved in NASH progression by analysis of pathophysiological features and gene-expression profiles in livers of STAM mice, a model of NASH-associated hepatocarcinogenesis. C57BL/6N (B6N) mice were injected with streptozotocin to generate STAM mice. Four-week-old male STAM and B6N mice were fed a high-fat diet (HFD) (STAM-F, B6N-F) or a conventional diet (STAM-C, B6N-C) until they were 10, 14, or 18 weeks old. Blood glucose and nonalcoholic fatty liver disease (NAFLD) activity scores of STAM-F were higher than those of STAM-C during all observation periods. STAM-F mice had more severe hepatic fibrosis at 14 weeks, and exhibited higher levels of α-fetoprotein-positive hepatic tumor formation with multiplication than STAM-C mice at 18 weeks. At 14 weeks, cDNA microarray analysis revealed that the hepatic expression of eight mRNAs was ≥30-fold higher in STAM-F than B6N-F mice. The expression of another four genes was increased ≥5-fold in STAM-F than B6N-F mice, and ≥5-fold in B6N-F relative to B6N-C mice. Of the 12 genes, the difference in Sptlc3 mRNA expression was most pronounced, and gradually increased over time, as determined by quantitative RT-PCR in STAM-F mice. In addition, Sptlc3 mRNA expression in STAM-F mice was higher than that in db/db mice that received HFD and in B6N mice fed a choline‑deficient L-amino acid (CDAA)-defined diet. In conclusion, a high-fat diet aggravated pathophysiological findings in the liver in NASH mouse models, and the hepatic expression of Sptlc3 mRNA was potentially associated with NASH progression.
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Affiliation(s)
- Yozo Yoshimine
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Hirofumi Uto
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Kotaro Kumagai
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Seiichi Mawatari
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Shiho Arima
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Rie Ibusuki
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Kumiko Mera
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Tsuyoshi Nosaki
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Shuji Kanmura
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Masatsugu Numata
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Tsutomu Tamai
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Akihiro Moriuchi
- Department of HGF Tissue Repair and Regenerative Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Hirohito Tsubouchi
- Department of HGF Tissue Repair and Regenerative Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Akio Ido
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
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Ernst D, Murphy SM, Sathiyanadan K, Wei Y, Othman A, Laurá M, Liu YT, Penno A, Blake J, Donaghy M, Houlden H, Reilly MM, Hornemann T. Novel HSAN1 mutation in serine palmitoyltransferase resides at a putative phosphorylation site that is involved in regulating substrate specificity. Neuromolecular Med 2015; 17:47-57. [PMID: 25567748 PMCID: PMC4326654 DOI: 10.1007/s12017-014-8339-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 12/17/2014] [Indexed: 02/04/2023]
Abstract
1-Deoxysphingolipids (1-deoxySL) are atypical sphingolipids that are formed by the enzyme serine palmitoyltransferase (SPT) due to a promiscuous use of l-alanine over its canonical substrate l-serine. Several mutations in SPT are associated with the hereditary sensory and autonomic neuropathy type I (HSAN1). The current hypothesis is that these mutations induce a permanent shift in the affinity from l-serine toward l-alanine which results in a pathologically increased 1-deoxySL formation in HSAN1 patients. Also, wild-type SPT forms 1-deoxySL under certain conditions, and elevated levels were found in individuals with the metabolic syndrome and diabetes. However, the molecular mechanisms which control the substrate shift of the wild-type enzyme are not understood. Here, we report a novel SPTLC2–S384F variant in two unrelated HSAN1 families. Affected patients showed elevated plasma 1-deoxySL levels and expression of the S384F mutant in HEK293 cells increased 1-deoxySL formation. Previously, S384 has been reported as one of the two (S384 and Y387) putative phosphorylation sites in SPTLC2. The phosphorylation of wild-type SPTLC2 was confirmed by isoelectric focusing. The impact of an S384 phosphorylation on SPT activity was tested by creating mutants mimicking either a constitutively phosphorylated (S384D, S384E) or non-phosphorylated (S384A, Y387F, Y387F+S384A) protein. The S384D but not the S384E variant was associated with increased 1-deoxySL formation. The other mutations had no influence on activity and substrate affinity. In summary, our data show that S384F is a novel mutation in HSAN1 and that the substrate specificity of wild-type SPT might by dynamically regulated by a phosphorylation at this position.
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Affiliation(s)
- Daniela Ernst
- Institute for Clinical Chemistry, University Hospital Zurich, CH-8091 Zurich, Switzerland
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, CH-8057 Zurich, Switzerland
| | - Sinéad M. Murphy
- Department of Neurology, Adelaide & Meath Hospitals Incorporating the National Children’s Hospital, Tallaght, Dublin 24, Ireland
- Academic Unit of Neurology, Trinity College Dublin, Dublin, Ireland
- Department of Molecular Neurosciences, MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, Queen Square, London, UK
| | | | - Yu Wei
- Institute for Clinical Chemistry, University Hospital Zurich, CH-8091 Zurich, Switzerland
| | - Alaa Othman
- Institute for Clinical Chemistry, University Hospital Zurich, CH-8091 Zurich, Switzerland
- Competence Center for Systems Physiology and Metabolic Diseases, Zuerich, Switzerland
| | - Matilde Laurá
- Department of Molecular Neurosciences, MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, Queen Square, London, UK
| | - Yo-Tsen Liu
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
- National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Anke Penno
- Life and Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany
| | - Julian Blake
- Department of Clinical Neurophysiology, The National Hospital for Neurology and Neurosurgery, London, UK
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
- Department of Clinical Neurophysiology, Norfolk and Norwich University Hospital, Norwich, UK
| | - Michael Donaghy
- Nuffield Department of Clinical Neuroscience, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Henry Houlden
- Department of Molecular Neurosciences, MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, Queen Square, London, UK
| | - Mary M. Reilly
- Department of Molecular Neurosciences, MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, Queen Square, London, UK
| | - Thorsten Hornemann
- Institute for Clinical Chemistry, University Hospital Zurich, CH-8091 Zurich, Switzerland
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, CH-8057 Zurich, Switzerland
- Life and Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany
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82
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Othman A, Saely CH, Muendlein A, Vonbank A, Drexel H, von Eckardstein A, Hornemann T. Plasma 1-deoxysphingolipids are predictive biomarkers for type 2 diabetes mellitus. BMJ Open Diabetes Res Care 2015; 3:e000073. [PMID: 25815206 PMCID: PMC4368929 DOI: 10.1136/bmjdrc-2014-000073] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 01/29/2015] [Accepted: 02/24/2015] [Indexed: 12/18/2022] Open
Abstract
OBJECTIVE Serine palmitoyltransferase (SPT) catalyzes the condensation of serine and palmitoyl coenzyme A, the first step in the de novo sphingolipid synthesis. Apart from these canonical substrates, SPT can also metabolize alanine and other acyl coenzyme As. This forms a spectrum of atypical sphingoid bases which are altered in the context of the metabolic syndrome (MetS) and type 2 diabetes mellitus (T2DM). We investigated whether atypical sphingolipids can be used as prospective markers to predict the incidence of T2DM. RESEARCH DESIGN AND METHODS Using liquid chromatography/mass spectrometry, we analyzed the sphingoid base profile in a prospective cohort with 339 individuals. All individuals were followed up for a period of 8 years. RESULTS Confirming earlier results, we found 1-deoxysphingolipids (1-deoxySLs) to be significantly elevated in patients with MetS, impaired fasting glucose, and T2DM. Patients who developed T2DM during the follow-up period (n=32) showed significantly higher 1-deoxySL levels at baseline compared with those who did not develop T2DM until the end of the study (n=70). 1-Deoxysphingosine levels were independent predictors for T2DM even after adjusting for glycated hemoglobin (standardized adjusted OR=2.1, CI 95% (1.19 to 3.71); p=0.010), MetS (standardized adjusted OR=1.97, CI 95% (1.13 to 3.43); p=0.017), and other risk factors such as age, sex, BMI, and lipid-lowering drugs. Similar results were observed for the 1-deoxysphinganine levels. CONCLUSIONS Our results support a novel role for 1-deoxySL as predictive biomarkers for the development of T2DM in risk patients and warrants further larger prospective trials in lower risk cohorts.
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Affiliation(s)
- Alaa Othman
- Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
- Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany
| | - Christoph H Saely
- Vorarlberg Institute for Vascular Investigation and Treatment (VIVIT), Feldkirch, Austria
- Department of Medicine and Cardiology, Academic Teaching Hospital Feldkirch, Feldkirch, Austria
- Private University of the Principality of Liechtenstein, Triesen, Liechtenstein
| | - Axel Muendlein
- Vorarlberg Institute for Vascular Investigation and Treatment (VIVIT), Feldkirch, Austria
- Department of Medicine and Cardiology, Academic Teaching Hospital Feldkirch, Feldkirch, Austria
- Private University of the Principality of Liechtenstein, Triesen, Liechtenstein
| | - Alexander Vonbank
- Vorarlberg Institute for Vascular Investigation and Treatment (VIVIT), Feldkirch, Austria
- Department of Medicine and Cardiology, Academic Teaching Hospital Feldkirch, Feldkirch, Austria
- Private University of the Principality of Liechtenstein, Triesen, Liechtenstein
| | - Heinz Drexel
- Vorarlberg Institute for Vascular Investigation and Treatment (VIVIT), Feldkirch, Austria
- Department of Medicine and Cardiology, Academic Teaching Hospital Feldkirch, Feldkirch, Austria
- Private University of the Principality of Liechtenstein, Triesen, Liechtenstein
- Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Arnold von Eckardstein
- Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
- Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Thorsten Hornemann
- Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
- Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
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83
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Schiffmann R. The consequences of genetic and pharmacologic reduction in sphingolipid synthesis. J Inherit Metab Dis 2015; 38:77-84. [PMID: 25164785 DOI: 10.1007/s10545-014-9758-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 07/28/2014] [Accepted: 07/31/2014] [Indexed: 10/24/2022]
Abstract
A new therapy based on substrate synthesis reduction in sphingolipidoses is showing promise. The consequences of decreasing sphingolipid synthesis depend on the level at which synthetic blockage occurs and on the extent of the blockage. Complete synthetic blockage may be lethal if it includes all sphingolipids, such as in a global knockout of serine palmitoyltransferase. Partial inhibition of sphingolipid synthetic pathways is usually benign and may have beneficial effects in a number of lysosomal diseases and in more common pathologies, as seen in animal models for atherosclerosis, polycystic kidney disease, diabetes, and asthma. Studies of various forms of sphingolipid synthesis reduction serve to highlight not only the cellular role of these lipids but also the potential risks and therapeutic benefits of pharmacological agents to be used in therapy for human diseases.
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Affiliation(s)
- Raphael Schiffmann
- Institute of Metabolic Disease, Baylor Research Institute, 3812 Elm Street, Dallas, TX, USA,
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84
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Yamaji T, Hanada K. Sphingolipid metabolism and interorganellar transport: localization of sphingolipid enzymes and lipid transfer proteins. Traffic 2014; 16:101-22. [PMID: 25382749 DOI: 10.1111/tra.12239] [Citation(s) in RCA: 289] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 10/29/2014] [Accepted: 11/06/2014] [Indexed: 11/28/2022]
Abstract
In recent decades, many sphingolipid enzymes, sphingolipid-metabolism regulators and sphingolipid transfer proteins have been isolated and characterized. This review will provide an overview of the intracellular localization and topology of sphingolipid enzymes in mammalian cells to highlight the locations where respective sphingolipid species are produced. Interestingly, three sphingolipids that reside or are synthesized in cytosolic leaflets of membranes (ceramide, glucosylceramide and ceramide-1-phosphate) all have cytosolic lipid transfer proteins (LTPs). These LTPs consist of ceramide transfer protein (CERT), four-phosphate adaptor protein 2 (FAPP2) and ceramide-1-phosphate transfer protein (CPTP), respectively. These LTPs execute functions that affect both the location and metabolism of the lipids they bind. Molecular details describing the mechanisms of regulation of LTPs continue to emerge and reveal a number of critical processes, including competing phosphorylation and dephosphorylation reactions and binding interactions with regulatory proteins and lipids that influence the transport, organelle distribution and metabolism of sphingolipids.
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Affiliation(s)
- Toshiyuki Yamaji
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan
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85
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Stimpson SE, Coorssen JR, Myers SJ. Mitochondrial protein alterations in a familial peripheral neuropathy caused by the V144D amino acid mutation in the sphingolipid protein, SPTLC1. J Chem Biol 2014; 8:25-35. [PMID: 25584079 DOI: 10.1007/s12154-014-0125-x] [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: 07/17/2014] [Accepted: 10/29/2014] [Indexed: 11/25/2022] Open
Abstract
Axonal degeneration is the final common path in many neurological disorders. Subsets of neuropathies involving the sensory neuron are known as hereditary sensory neuropathies (HSNs). Hereditary sensory neuropathy type I (HSN-I) is the most common subtype of HSN with autosomal dominant inheritance. It is characterized by the progressive degeneration of the dorsal root ganglion (DRG) with clinical symptom onset between the second or third decade of life. Heterozygous mutations in the serine palmitoyltransferase (SPT) long chain subunit 1 (SPTLC1) gene were identified as the pathogenic cause of HSN-I. Ultrastructural analysis of mitochondria from HSN-I patient cells has displayed unique morphological abnormalities that are clustered to the perinucleus where they are wrapped by the endoplasmic reticulum (ER). This investigation defines a small subset of proteins with major alterations in abundance in mitochondria harvested from HSN-I mutant SPTLC1 cells. Using mitochondrial protein isolates from control and patient lymphoblasts, and a combination of 2D gel electrophoresis, immunoblotting and mass spectrometry, we have shown the increased abundance of ubiquinol-cytochrome c reductase core protein 1, an electron transport chain protein, as well as the immunoglobulin, Ig kappa chain C. The regulation of these proteins may provide a new route to understanding the cellular and molecular mechanisms underlying HSN-I.
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Affiliation(s)
- Scott E Stimpson
- Neuro-Cell Biology Laboratory, University of Western Sydney, Penrith, Australia ; Molecular Medicine Research Group, University of Western Sydney, Penrith, Australia ; School of Science and Health, University of Western Sydney, Penrith, Australia
| | - Jens R Coorssen
- Molecular Physiology, University of Western Sydney, Penrith, Australia ; Molecular Medicine Research Group, University of Western Sydney, Penrith, Australia ; School of Science and Health, University of Western Sydney, Penrith, Australia ; School of Medicine, University of Western Sydney, Locked Bag 1797, Penrith, NSW 2751 Australia ; School of Medicine, University of Western Sydney, Office 30.2.15, Campbelltown campus, Locked Bag 1797, Penrith, NSW 2751 Australia
| | - Simon J Myers
- Neuro-Cell Biology Laboratory, University of Western Sydney, Penrith, Australia ; Molecular Medicine Research Group, University of Western Sydney, Penrith, Australia ; School of Science and Health, University of Western Sydney, Penrith, Australia ; School of Medicine, University of Western Sydney, Locked Bag 1797, Penrith, NSW 2751 Australia ; University of Western Sydney, Office 21.1.05, Campbelltown campus, Locked Bag 1797, Penrith, NSW 2751 Australia
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86
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Gulshan K, Smith J. Sphingomyelin regulation of plasma membrane asymmetry, efflux and reverse cholesterol transport. ACTA ACUST UNITED AC 2014. [DOI: 10.2217/clp.14.28] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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87
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Wojcik GL, Thio CL, Kao WHL, Latanich R, Goedert JJ, Mehta SH, Kirk GD, Peters MG, Cox AL, Kim AY, Chung RT, Thomas DL, Duggal P. Admixture analysis of spontaneous hepatitis C virus clearance in individuals of African descent. Genes Immun 2014; 15:241-6. [PMID: 24622687 PMCID: PMC4308959 DOI: 10.1038/gene.2014.11] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/17/2013] [Accepted: 12/19/2013] [Indexed: 12/19/2022]
Abstract
Hepatitis C virus (HCV) infects an estimated 3% of the global population with the majority of individuals (75-85%) failing to clear the virus without treatment, leading to chronic liver disease. Individuals of African descent have lower rates of clearance compared with individuals of European descent and this is not fully explained by social and environmental factors. This suggests that differences in genetic background may contribute to this difference in clinical outcome following HCV infection. Using 473 individuals and 792,721 single-nucleotide polymorphisms (SNPs) from a genome-wide association study (GWAS), we estimated local African ancestry across the genome. Using admixture mapping and logistic regression, we identified two regions of interest associated with spontaneous clearance of HCV (15q24, 20p12). A genome-wide significant variant was identified on chromosome 15 at the imputed SNP, rs55817928 (P=6.18 × 10(-8)) between the genes SCAPER and RCN. Each additional copy of the African ancestral C allele is associated with 2.4 times the odds of spontaneous clearance. Conditional analysis using this SNP in the logistic regression model explained one-third of the local ancestry association. Additionally, signals of selection in this area suggest positive selection due to some ancestral pathogen or environmental pressure in African, but not in European populations.
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Affiliation(s)
- G L Wojcik
- Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - C L Thio
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - W H L Kao
- 1] Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA [2] Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - R Latanich
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - J J Goedert
- Infections and Immunoepidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD, USA
| | - S H Mehta
- Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - G D Kirk
- Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - M G Peters
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - A L Cox
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - A Y Kim
- Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - R T Chung
- Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - D L Thomas
- 1] Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA [2] Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - P Duggal
- Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
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88
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Increased lipid droplet accumulation associated with a peripheral sensory neuropathy. J Chem Biol 2014; 7:67-76. [PMID: 24711860 DOI: 10.1007/s12154-014-0108-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 03/03/2014] [Indexed: 12/11/2022] Open
Abstract
Hereditary sensory neuropathy type 1 (HSN-1) is an autosomal dominant neurodegenerative disease caused by missense mutations in the SPTLC1 gene. The SPTLC1 protein is part of the SPT enzyme which is a ubiquitously expressed, critical and thus highly regulated endoplasmic reticulum bound membrane enzyme that maintains sphingolipid concentrations and thus contributes to lipid metabolism, signalling, and membrane structural functions. Lipid droplets are dynamic organelles containing sphingolipids and membrane bound proteins surrounding a core of neutral lipids, and thus mediate the intracellular transport of these specific molecules. Current literature suggests that there are increased numbers of lipid droplets and alterations of lipid metabolism in a variety of other autosomal dominant neurodegenerative diseases, including Alzheimer's and Parkinson's disease. This study establishes for the first time, a significant increase in the presence of lipid droplets in HSN-1 patient-derived lymphoblasts, indicating a potential connection between lipid droplets and the pathomechanism of HSN-1. However, the expression of adipophilin (ADFP), which has been implicated in the regulation of lipid metabolism, was not altered in lipid droplets from the HSN-1 patient-derived lymphoblasts. This appears to be the first report of increased lipid body accumulation in a peripheral neuropathy, suggesting a fundamental molecular linkage between a number of neurodegenerative diseases.
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89
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Cinar R, Godlewski G, Liu J, Tam J, Jourdan T, Mukhopadhyay B, Harvey-White J, Kunos G. Hepatic cannabinoid-1 receptors mediate diet-induced insulin resistance by increasing de novo synthesis of long-chain ceramides. Hepatology 2014; 59:143-53. [PMID: 23832510 PMCID: PMC3839256 DOI: 10.1002/hep.26606] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Accepted: 06/20/2013] [Indexed: 12/14/2022]
Abstract
UNLABELLED Obesity is associated with increased activity of two lipid signaling systems (endocannabinoids [ECs] and ceramides), with both being implicated in insulin resistance. Cannabinoid-1 receptor (CB1 R) antagonists reverse obesity and insulin resistance, but have psychiatric side effects. Here we analyzed the role of ceramide in CB1 R-mediated insulin resistance in C57Bl6/J mice with high-fat diet-induced obesity (DIO), using JD5037, a peripherally restricted CB1 R inverse agonist. Chronic JD5037 treatment of DIO mice reduced body weight and steatosis and improved glucose tolerance and insulin sensitivity. Peripheral CB1 R blockade also attenuated the diet-induced increase in C14:0, C16:0, C18:0, and C20:0 ceramide species with either C16 or C18 sphingosine-base in the liver. Decreased ceramide levels reflected their reduced de novo synthesis, due to inhibition of the activity of serine-palmitoyl transferase (SPT) and the expression of its SPTLC3 catalytic subunit, as well as reduced ceramide synthase (CerS) activity related to reduced expression of CerS1 and CerS6. JD5037 treatment also increased ceramide degradation due to increased expression of ceramidases. In primary cultured mouse hepatocytes and HepG2 cells, the EC anandamide increased ceramide synthesis in an eIF2α-dependent manner, and inhibited insulin-induced akt phosphorylation by increased serine phosphorylation of IRS1 and increased expression of the serine/threonine phosphatase Phlpp1. These effects were abrogated by JD5037 or the SPT inhibitor myriocin. Chronic treatment of DIO mice with myriocin or JD5037 similarly reversed hepatic insulin resistance, as verified using a euglycemic/hyperinsulinemic clamp. CONCLUSION ECs induce CB1 R-mediated, endoplasmic reticulum stress-dependent synthesis of specific ceramide subspecies in the liver, which plays a key role in obesity-related hepatic insulin resistance.
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Affiliation(s)
- Resat Cinar
- Laboratory of Physiological Studies; National Institute on Alcohol Abuse and Alcoholism; National Institutes of Health; Bethesda MD
| | - Grzegorz Godlewski
- Laboratory of Physiological Studies; National Institute on Alcohol Abuse and Alcoholism; National Institutes of Health; Bethesda MD
| | - Jie Liu
- Laboratory of Physiological Studies; National Institute on Alcohol Abuse and Alcoholism; National Institutes of Health; Bethesda MD
| | - Joseph Tam
- Laboratory of Physiological Studies; National Institute on Alcohol Abuse and Alcoholism; National Institutes of Health; Bethesda MD
| | - Tony Jourdan
- Laboratory of Physiological Studies; National Institute on Alcohol Abuse and Alcoholism; National Institutes of Health; Bethesda MD
| | - Bani Mukhopadhyay
- Laboratory of Physiological Studies; National Institute on Alcohol Abuse and Alcoholism; National Institutes of Health; Bethesda MD
| | - Judith Harvey-White
- Laboratory of Physiological Studies; National Institute on Alcohol Abuse and Alcoholism; National Institutes of Health; Bethesda MD
| | - George Kunos
- Laboratory of Physiological Studies; National Institute on Alcohol Abuse and Alcoholism; National Institutes of Health; Bethesda MD
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90
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Caretti A, Bragonzi A, Facchini M, De Fino I, Riva C, Gasco P, Musicanti C, Casas J, Fabriàs G, Ghidoni R, Signorelli P. Anti-inflammatory action of lipid nanocarrier-delivered myriocin: therapeutic potential in cystic fibrosis. Biochim Biophys Acta Gen Subj 2013; 1840:586-94. [PMID: 24141140 DOI: 10.1016/j.bbagen.2013.10.018] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 09/07/2013] [Accepted: 10/10/2013] [Indexed: 11/26/2022]
Abstract
BACKGROUND Sphingolipids take part in immune response and can initiate and/or sustain inflammation. Various inflammatory diseases have been associated with increased ceramide content, and pharmacological reduction of ceramide diminishes inflammation damage in vivo. Inflammation and susceptibility to microbial infection are two elements in a vicious circle. Recently, sphingolipid metabolism inhibitors were used to reduce infection. Cystic fibrosis (CF) is characterized by a hyper-inflammation and an excessive innate immune response, which fails to evolve into adaptive immunity and to eradicate infection. Chronic infections result in lung damage and patient morbidity. Notably, ceramide content in mucosa airways is higher in CF mouse models and in patients than in control mice or healthy subjects. METHODS The therapeutic potential of myriocin, an inhibitor of the sphingolipid de novo synthesis rate limiting enzyme (Serine Palmitoyl Transferase, SPT),was investigated in CF cells and mice models. RESULTS We treated CF human respiratory epithelial cells with myriocin, This treatment resulted in reduced basal, as well as TNFα-stimulated, inflammation. In turn, TNFα induced an increase in SPT in these cells, linking de novo synthesis of ceramide to inflammation. Furthermore, myriocin-loaded nanocarrier, injected intratrachea prior to P. aeruginosa challenge, enabled a significant reduction of lung infection and reduced inflammation. CONCLUSIONS The presented data suggest that de novo ceramide synthesis is constitutively enhanced in CF mucosa and that it can be envisaged as pharmacological target for modulating inflammation and restoring effective innate immunity against acute infection. GENERAL SIGNIFICANCE Myriocin stands as a powerful immunomodulatory agent for inflammatory and infectious diseases.
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Affiliation(s)
- Anna Caretti
- Department of Health Sciences, University of Milan, San Paolo Hospital, Italy
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91
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Rego A, Trindade D, Chaves SR, Manon S, Costa V, Sousa MJ, Côrte-Real M. The yeast model system as a tool towards the understanding of apoptosis regulation by sphingolipids. FEMS Yeast Res 2013; 14:160-78. [DOI: 10.1111/1567-1364.12096] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 08/02/2013] [Accepted: 09/06/2013] [Indexed: 11/30/2022] Open
Affiliation(s)
- António Rego
- Departamento de Biologia; Centro de Biologia Molecular e Ambiental; Universidade do Minho; Braga Portugal
- Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto Portugal
| | - Dário Trindade
- Departamento de Biologia; Centro de Biologia Molecular e Ambiental; Universidade do Minho; Braga Portugal
- CNRS; UMR5095; Université de Bordeaux 2; Bordeaux France
| | - Susana R. Chaves
- Departamento de Biologia; Centro de Biologia Molecular e Ambiental; Universidade do Minho; Braga Portugal
| | - Stéphen Manon
- CNRS; UMR5095; Université de Bordeaux 2; Bordeaux France
| | - Vítor Costa
- Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto Portugal
- Departamento de Biologia Molecular; Instituto de Ciências Biomédicas Abel Salazar; Universidade do Porto; Porto Portugal
| | - Maria João Sousa
- Departamento de Biologia; Centro de Biologia Molecular e Ambiental; Universidade do Minho; Braga Portugal
| | - Manuela Côrte-Real
- Departamento de Biologia; Centro de Biologia Molecular e Ambiental; Universidade do Minho; Braga Portugal
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92
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The pyridoxal 5'-phosphate (PLP)-dependent enzyme serine palmitoyltransferase (SPT): effects of the small subunits and insights from bacterial mimics of human hLCB2a HSAN1 mutations. BIOMED RESEARCH INTERNATIONAL 2013; 2013:194371. [PMID: 24175284 PMCID: PMC3794620 DOI: 10.1155/2013/194371] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 07/22/2013] [Indexed: 12/03/2022]
Abstract
The pyridoxal 5′-phosphate (PLP)-dependent enzyme serine palmitoyltransferase (SPT) catalyses the first step of de novo sphingolipid biosynthesis. The core human enzyme is a membrane-bound heterodimer composed of two subunits (hLCB1 and hLCB2a/b), and mutations in both hLCB1 (e.g., C133W and C133Y) and hLCB2a (e.g., V359M, G382V, and I504F) have been identified in patients with hereditary sensory and autonomic neuropathy type I (HSAN1), an inherited disorder that affects sensory and autonomic neurons. These mutations result in substrate promiscuity, leading to formation of neurotoxic deoxysphingolipids found in affected individuals. Here we measure the activities of the hLCB2a mutants in the presence of ssSPTa and ssSPTb and find that all decrease enzyme activity. High resolution structural data of the homodimeric SPT enzyme from the bacterium Sphingomonas paucimobilis (Sp SPT) provides a model to understand the impact of the hLCB2a mutations on the mechanism of SPT. The three human hLCB2a HSAN1 mutations map onto Sp SPT (V246M, G268V, and G385F), and these mutant mimics reveal that the amino acid changes have varying impacts; they perturb the PLP cofactor binding, reduce the affinity for both substrates, decrease the enzyme activity, and, in the most severe case, cause the protein to be expressed in an insoluble form.
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93
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Brozinick JT, Hawkins E, Hoang Bui H, Kuo MS, Tan B, Kievit P, Grove K. Plasma sphingolipids are biomarkers of metabolic syndrome in non-human primates maintained on a Western-style diet. Int J Obes (Lond) 2013; 37:1064-70. [PMID: 23207405 PMCID: PMC3718866 DOI: 10.1038/ijo.2012.191] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 10/09/2012] [Accepted: 10/16/2012] [Indexed: 12/18/2022]
Abstract
BACKGROUND The intake of a Western diet enriched in animal fat has been shown to be a major risk factor for Type 2 diabetes and obesity. Previous rodent studies have indicated that these conditions may be triggered by the accumulation of the sphingolipid ceramide in insulin-sensitive tissues. However, data are lacking in this regard from both humans and non-human primates. OBJECTIVE Here we have investigated the relationship between plasma ceramides and metabolic syndrome in Rhesus macaques fed a high-fat and high-fructose (HFFD) 'western' diet. METHODS We investigated this relationship in cohorts of monkeys fed a HFFD for a period of 8 months to 5 years. Animals were classified as control, pre-diabetic or diabetic based on fasting plasma parameters and insulin sensitivity. RESULTS HFFD treatment produced significant increases in body weight and body fat and also resulted in a decline in insulin sensitivity. In parallel to the reduction in insulin sensitivity, significant increases in both plasma ceramide and dihydroceramide levels were observed, which further increased as animals progressed to the diabetic state. Plasma levels of the rare sphingolipid C18:0 deoxysphinganine, a marker of increased metabolic flux through serine palmitoyl transferase (SPT), were also elevated in both pre- and diabetic animals. Furthermore, plasma serine levels were significantly elevated in diabetic monkeys, which may indicate a shift in SPT substrate selectivity from serine to alanine or glycine. In contrast, branch chain amino acids were unchanged in pre-diabetic non-human primates, and only plasma valine levels were elevated in diabetic animals. CONCLUSION Together, these data indicate that HFFD induces de novo synthesis of ceramides in non-human primates, and that increased production of plasma ceramides is significantly correlated with the decline in insulin sensitivity.
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94
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Murphy SM, Ernst D, Wei Y, Laurà M, Liu YT, Polke J, Blake J, Winer J, Houlden H, Hornemann T, Reilly MM. Hereditary sensory and autonomic neuropathy type 1 (HSANI) caused by a novel mutation in SPTLC2. Neurology 2013; 80:2106-11. [PMID: 23658386 DOI: 10.1212/wnl.0b013e318295d789] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To describe the clinical and neurophysiologic phenotype of a family with hereditary sensory and autonomic neuropathy type 1 (HSANI) due to a novel mutation in SPTLC2 and to characterize the biochemical properties of this mutation. METHODS We screened 107 patients with HSAN who were negative for other genetic causes for mutations in SPTLC2. The biochemical properties of a new mutation were characterized in cell-free and cell-based activity assays. RESULTS A novel mutation (A182P) was found in 2 subjects of a single family. The phenotype of the 2 subjects was an ulcero-mutilating sensory-predominant neuropathy as described previously for patients with HSANI, but with prominent motor involvement and earlier disease onset in the first decade of life. Affected patients had elevated levels of plasma 1-deoxysphingolipids (1-deoxySLs). Biochemically, the A182P mutation was associated with a reduced canonical activity but an increased alternative activity with alanine, which results in largely increased 1-deoxySL levels, supporting their pathogenicity. CONCLUSION This study confirms that mutations in SPTLC2 are associated with increased deoxySL formation causing HSANI.
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Affiliation(s)
- Sinéad M Murphy
- MRC Centre for Neuromuscular Diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, UK
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95
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Tidhar R, Futerman AH. The complexity of sphingolipid biosynthesis in the endoplasmic reticulum. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2511-8. [PMID: 23611790 DOI: 10.1016/j.bbamcr.2013.04.010] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 04/03/2013] [Accepted: 04/08/2013] [Indexed: 12/21/2022]
Abstract
Unlike the synthesis of other membrane lipids, sphingolipid synthesis is compartmentalized between the endoplasmic reticulum and the Golgi apparatus. The initial steps of sphingolipid synthesis, from the activity of serine palmitoyltransferase through to dihydroceramide desaturase, take place in the endoplasmic reticulum, but the further metabolism of ceramide to sphingomyelin and complex glycosphingolipids takes place mostly in the Golgi apparatus. Studies over the last decade or so have revealed unexpected levels of complexity in the sphingolipid biosynthetic pathway, mainly due to either the promiscuity of some enzymes towards their substrates, or the tight selectivity of others towards specific substrates. We now discuss two enzymes in this pathway, namely serine palmitoyltransferase (SPT) and ceramide synthase (CerS), and one lipid transport protein, CERT. For SPT and CERT, significant structural information is available, and for CerS, significant information has recently been obtained that sheds light of the roles of the specific ceramide species that are produced by each of the CerS. We consider the mechanisms by which specificity is generated and speculate on the reasons that sphingolipid biosynthesis is so complex. This article is part of a Special Issue entitled: Functional and structural diversity of endoplasmic reticulum.
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Affiliation(s)
- Rotem Tidhar
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
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96
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Russo SB, Tidhar R, Futerman AH, Cowart LA. Myristate-derived d16:0 sphingolipids constitute a cardiac sphingolipid pool with distinct synthetic routes and functional properties. J Biol Chem 2013; 288:13397-409. [PMID: 23530041 DOI: 10.1074/jbc.m112.428185] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Myristate is a novel potential substrate for sphingoid base synthesis. RESULTS Myocardial sphingoid base synthesis utilizes myristate; these sphingolipids are functionally non-redundant with canonical sphingoid bases. CONCLUSION d16:0 and d16:1 sphingolipids constitute an appreciable proportion of cardiac dihydrosphingosine and dihydroceramide, with distinct biological roles. SIGNIFICANCE This pool of sphingolipids may play a heretofore unsuspected role in myocardial pathology or protection. The enzyme serine palmitoyltransferase (SPT) catalyzes the formation of the sphingoid base "backbone" from which all sphingolipids are derived. Previous studies have shown that inhibition of SPT ameliorates pathological cardiac outcomes in models of lipid overload, but the metabolites responsible for these phenotypes remain unidentified. Recent in vitro studies have shown that incorporation of the novel subunit SPTLC3 broadens the substrate specificity of SPT, allowing utilization of myristoyl-coenzyme A (CoA) in addition to its canonical substrate palmitoyl-CoA. However, the relevance of these findings in vivo has yet to be determined. The present study sought to determine whether myristate-derived d16 sphingolipids are represented among myocardial sphingolipids and, if so, whether their function and metabolic routes were distinct from those of palmitate-derived d18 sphingolipids. Data showed that d16:0 sphingoid bases occurred in more than one-third of total dihydrosphingosine and dihydroceramides in myocardium, and a diet high in saturated fat promoted their de novo production. Intriguingly, d16-ceramides demonstrated highly limited N-acyl chain diversity, and in vitro enzyme activity assays showed that these bases were utilized preferentially to canonical bases by CerS1. Functional differences between myristate- and palmitate-derived sphingolipids were observed in that, unlike d18 sphingolipids and SPTLC2, d16 sphingolipids and SPTLC3 did not appear to contribute to myristate-induced autophagy, whereas only d16 sphingolipids promoted cell death and cleavage of poly(ADP-ribose) polymerase in cardiomyocytes. Thus, these results reveal a previously unappreciated component of cardiac sphingolipids with functional differences from canonical sphingolipids.
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Affiliation(s)
- Sarah Brice Russo
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29403, USA
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97
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Chakraborty M, Lou C, Huan C, Kuo MS, Park TS, Cao G, Jiang XC. Myeloid cell-specific serine palmitoyltransferase subunit 2 haploinsufficiency reduces murine atherosclerosis. J Clin Invest 2013; 123:1784-97. [PMID: 23549085 DOI: 10.1172/jci60415] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 01/24/2013] [Indexed: 12/15/2022] Open
Abstract
Serine palmitoyltransferase (SPT) is the first and rate-limiting enzyme of the de novo biosynthetic pathway of sphingomyelin (SM). Both SPT and SM have been implicated in the pathogenesis of atherosclerosis, the development of which is driven by macrophages; however, the role of SPT in macrophage-mediated atherogenesis is unknown. To address this issue, we have analyzed macrophage inflammatory responses and reverse cholesterol transport, 2 key mediators of atherogenesis, in SPT subunit 2-haploinsufficient (Sptlc2(+/-)) macrophages. We found that Sptlc2(+/-) macrophages have significantly lower SM levels in plasma membrane and lipid rafts. This reduction not only impaired inflammatory responses triggered by TLR4 and its downstream NF-κB and MAPK pathways, but also enhanced reverse cholesterol transport mediated by ABC transporters. LDL receptor-deficient (Ldlr(-/-)) mice transplanted with Sptlc2(+/-) bone marrow cells exhibited significantly fewer atherosclerotic lesions after high-fat and high-cholesterol diet feeding. Additionally, Ldlr(-/-) mice with myeloid cell-specific Sptlc2 haploinsufficiency exhibited significantly less atherosclerosis than controls. These findings suggest that SPT could be a novel therapeutic target in atherosclerosis.
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Affiliation(s)
- Mahua Chakraborty
- Department of Cell Biology, State University of New York Downstate Medical Center, New York, New York, USA
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98
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Harmon JM, Bacikova D, Gable K, Gupta SD, Han G, Sengupta N, Somashekarappa N, Dunn TM. Topological and functional characterization of the ssSPTs, small activating subunits of serine palmitoyltransferase. J Biol Chem 2013; 288:10144-10153. [PMID: 23426370 DOI: 10.1074/jbc.m113.451526] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The topological and functional organization of the two isoforms of the small subunits of human serine palmitoyltransferase (hssSPTs) that activate the catalytic hLCB1/hLCB2 heterodimer was investigated. A variety of experimental approaches placed the N termini of the ssSPTs in the cytosol, their C termini in the lumen, and showed that they contain a single transmembrane domain. Deletion analysis revealed that the ability to activate the heterodimer is contained in a conserved 33-amino acid core domain that has the same membrane topology as the full-length protein. In combination with analysis of isoform chimera and site-directed mutagenesis, a single amino acid residue in this core (Met(25) in ssSPTa and Val(25) in ssSPTb) was identified which confers specificity for palmitoyl- or stearoyl-CoA, respectively, in both yeast and mammalian cells. This same residue also determines which isoform is a better activator of a mutant heterodimer, hLCB1(S331F)/hLCB2a, which has increased basal SPT activity and decreased amino acid substrate selectivity. This suggests that the role of the ssSPTs is to increase SPT activity without compromising substrate specificity. In addition, the observation that the C-terminal domains of ssSPTa and ssSPTb, which are highly conserved within each subfamily but are the most divergent regions between isoform subfamilies, are not required for activation of the heterodimer or for acyl-CoA selectivity suggests that the ssSPTs have additional roles that remain to be discovered.
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Affiliation(s)
- Jeffrey M Harmon
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
| | - Dagmar Bacikova
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
| | - Kenneth Gable
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
| | - Sita D Gupta
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
| | - Gongshe Han
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
| | - Nivedita Sengupta
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
| | | | - Teresa M Dunn
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799.
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Hornemann T, Worgall TS. Sphingolipids and atherosclerosis. Atherosclerosis 2012; 226:16-28. [PMID: 23075523 DOI: 10.1016/j.atherosclerosis.2012.08.041] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 08/06/2012] [Accepted: 08/22/2012] [Indexed: 11/19/2022]
Abstract
The atherosclerotic lesion contains a high amount of sphingolipids, a large group of structurally diverse lipids that regulate distinct biological functions beyond their role as structural membrane components. Assessment of their role in atherogenesis has been enabled after genes that regulate their metabolism had been identified and facilitated by the more wide availability of mass spectrometry. Here we discuss recent mechanistic insights obtained in animal and epidemiological studies that have greatly enhanced our understanding of mechanisms how sphingolipids affect the atherosclerotic process.
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Affiliation(s)
- Thorsten Hornemann
- Inst. for Clinical Chemistry, University Hospital Zuerich, Raemistrasse 100, 8091 Zuerich, Switzerland.
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100
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Structural, mechanistic and regulatory studies of serine palmitoyltransferase. Biochem Soc Trans 2012; 40:547-54. [PMID: 22616865 DOI: 10.1042/bst20110769] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
SLs (sphingolipids) are composed of fatty acids and a polar head group derived from L-serine. SLs are essential components of all eukaryotic and many prokaryotic membranes but S1P (sphingosine 1-phosphate) is also a potent signalling molecule. Recent efforts have sought to inventory the large and chemically complex family of SLs (LIPID MAPS Consortium). Detailed understanding of SL metabolism may lead to therapeutic agents specifically directed at SL targets. We have studied the enzymes involved in SL biosynthesis; later stages are species-specific, but all core SLs are synthesized from the condensation of L-serine and a fatty acid thioester such as palmitoyl-CoA that is catalysed by SPT (serine palmitoyltransferase). SPT is a PLP (pyridoxal 5'-phosphate)-dependent enzyme that forms 3-KDS (3-ketodihydrosphingosine) through a decarboxylative Claisen-like condensation reaction. Eukaryotic SPTs are membrane-bound multi-subunit enzymes, whereas bacterial enzymes are cytoplasmic homodimers. We use bacterial SPTs (e.g. from Sphingomonas) to probe their structure and mechanism. Mutations in human SPT cause a neuropathy [HSAN1 (hereditary sensory and autonomic neuropathy type 1)], a rare SL metabolic disease. How these mutations perturb SPT activity is subtle and bacterial SPT mimics of HSAN1 mutants affect the enzyme activity and structure of the SPT dimer. We have also explored SPT inhibition using various inhibitors (e.g. cycloserine). A number of new subunits and regulatory proteins that have a direct impact on the activity of eukaryotic SPTs have recently been discovered. Knowledge gained from bacterial SPTs sheds some light on the more complex mammalian systems. In the present paper, we review historical aspects of the area and highlight recent key developments.
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