1
|
Downton P, Sanna F, Maidstone R, Poolman TM, Hayter EA, Dickson SH, Ciccone NA, Early JO, Adamson A, Spiller DG, Simpkins DA, Baxter M, Fischer R, Rattray M, Loudon ASI, Gibbs JE, Bechtold DA, Ray DW. Chronic inflammatory arthritis drives systemic changes in circadian energy metabolism. Proc Natl Acad Sci U S A 2022; 119:e2112781119. [PMID: 35482925 PMCID: PMC9170023 DOI: 10.1073/pnas.2112781119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 03/01/2022] [Indexed: 11/22/2022] Open
Abstract
Chronic inflammation underpins many human diseases. Morbidity and mortality associated with chronic inflammation are often mediated through metabolic dysfunction. Inflammatory and metabolic processes vary through circadian time, suggesting an important temporal crosstalk between these systems. Using an established mouse model of rheumatoid arthritis, we show that chronic inflammatory arthritis results in rhythmic joint inflammation and drives major changes in muscle and liver energy metabolism and rhythmic gene expression. Transcriptional and phosphoproteomic analyses revealed alterations in lipid metabolism and mitochondrial function associated with increased EGFR-JAK-STAT3 signaling. Metabolomic analyses confirmed rhythmic metabolic rewiring with impaired β-oxidation and lipid handling and revealed a pronounced shunt toward sphingolipid and ceramide accumulation. The arthritis-related production of ceramides was most pronounced during the day, which is the time of peak inflammation and increased reliance on fatty acid oxidation. Thus, our data demonstrate that localized joint inflammation drives a time-of-day–dependent build-up of bioactive lipid species driven by rhythmic inflammation and altered EGFR-STAT signaling.
Collapse
Affiliation(s)
- Polly Downton
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Fabio Sanna
- National Institute for Health Research Oxford Biomedical Research Centre, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 9DU, United Kingdom
| | - Robert Maidstone
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
- National Institute for Health Research Oxford Biomedical Research Centre, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 9DU, United Kingdom
| | - Toryn M. Poolman
- National Institute for Health Research Oxford Biomedical Research Centre, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 9DU, United Kingdom
| | - Edward A. Hayter
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Suzanna H. Dickson
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Nick A. Ciccone
- National Institute for Health Research Oxford Biomedical Research Centre, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 9DU, United Kingdom
| | - James O. Early
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Antony Adamson
- Genome Editing Unit, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - David G. Spiller
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Devin A. Simpkins
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Matthew Baxter
- National Institute for Health Research Oxford Biomedical Research Centre, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 9DU, United Kingdom
| | - Roman Fischer
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, OX3 7FZ, United Kingdom
| | - Magnus Rattray
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Andrew S. I. Loudon
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Julie E. Gibbs
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - David A. Bechtold
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - David W. Ray
- National Institute for Health Research Oxford Biomedical Research Centre, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 9DU, United Kingdom
| |
Collapse
|
2
|
Kumar R, de Vijver MV, Tortora G, Ciardiello F, Goldkorn T, Miller WH, Norton L. A Tribute to John Mendelsohn: A Pioneer in Targeted Cancer Therapy. Cancer Res 2019; 79:4315-4323. [PMID: 31213466 DOI: 10.1158/0008-5472.can-19-0989] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 05/01/2019] [Accepted: 05/28/2019] [Indexed: 11/16/2022]
Abstract
Cancer scientists and clinicians are mourning the death of one of the most accomplished members of their community: Dr. John Mendelsohn. He was a pioneer in targeted cancer therapy and was instrumental for the discovery and deployment of the first antagonist epidermal growth factor receptor (EGFR) therapeutic antibodies, broadening the concept of targeted EGFR therapy to encompass other receptor tyrosine kinases, such as HER2, and developing blocking antibody-combination therapy with chemotherapies or radiotherapy. Dr. Mendelsohn, who died on January 7, 2019, always led by the strength of his accomplishments and the humility of his character. Above all, he was a well-revered mentor and clinician, who extended compassion and the gift of his time to patients, colleagues, and mentees alike. In tribute to Dr. Mendelsohn, Cancer Research has invited his former mentees and colleagues who were associated with Dr. Mendelsohn for over three decades to reflect on the broad impact of his work. Here, we discuss Dr. Mendelsohn's illustrious career at three elite academic cancer institutions and hospitals in the United States, his acumen to build, grow, and uplift institutions, and train a generation of medical oncologists, physician scientists, and cancer biologists. His profound legacy on targeted therapy and cancer research and treatment continue to prolong and save the lives of cancer patients globally.
Collapse
Affiliation(s)
- Rakesh Kumar
- Cancer Biology Program, Rajiv Gandhi Centre for Biotechnology, Trivandrum, Kerala, India.
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
- Department of Medicine, Division of Hematology-Oncology, Rutgers New Jersey Medical School, Newark, New Jersey
| | - Marc Van de Vijver
- Department of Pathology, Academic Medical Center, Amsterdam, the Netherlands
| | - Giampaolo Tortora
- Medical Oncology, Comprehensive Cancer Center, Fondazione Policlinico Universitario Gemelli, IRCCS, Rome, Italy
- Medical Oncology, Catholic University of the Sacred Heart, Rome, Italy
| | - Fortunato Ciardiello
- Dipartimento di Medicina di Precisione, Università degli Studi della Campania Luigi Vanvitelli, Napoli, Italy
| | - Tzipora Goldkorn
- University of California Davis School of Medicine, Davis, California
| | - Wilson H Miller
- Department of Medicine, Segal Cancer Center and Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - Larry Norton
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York
| |
Collapse
|
3
|
Kitchen SA, Weis VM. The sphingosine rheostat is involved in the cnidarian heat stress response but not necessarily in bleaching. J Exp Biol 2017; 220:1709-1720. [DOI: 10.1242/jeb.153858] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Accepted: 02/16/2017] [Indexed: 12/17/2022]
Abstract
Sphingolipids play important roles in mitigating cellular heat and oxidative stress by altering membrane fluidity, receptor clustering and gene expression. Accumulation of signaling sphingolipids that comprise the sphingosine rheostat, pro-apoptotic sphingosine (Sph) and pro-survival sphingosine-1-phosphate (S1P), is key to determining cell fate. Reef-building corals and other symbiotic cnidarians living in shallow tropical waters can experience elevated seawater temperature and high UV irradiance, two stressors that are increasing in frequency and severity with climate change. In symbiotic cnidarians, these stressors disrupt the photosynthetic machinery of the endosymbiont and ultimately result in the collapse of the partnership (dysbiosis), known as cnidarian bleaching. In a previous study, exogenously applied sphingolipids altered heat-induced bleaching in the symbiotic anemone Aiptasia pallida, but endogenous regulation of these lipids is unknown. Here, we characterized the role of the rheostat in the cnidarian heat stress response (HSR) and in dysbiosis. Gene expression of rheostat enzymes sphingosine kinase (AP-SPHK) and S1P phosphatase (AP-SGPP), and concentrations of sphingolipids were quantified from anemones incubated at elevated temperatures. We observed a biphasic HSR in A. pallida. At early exposure, rheostat gene expression and lipid levels were suppressed while gene expression of a heat stress biomarker increased and 40% of symbionts were lost. After longer incubations at the highest temperature, AP-SGPP and then Sph levels both increased. These results indicate that the sphingosine rheostat in A. pallida does not participate in initiation of dysbiosis, but instead functions in the chronic response to prolonged heat stress that promotes host survival.
Collapse
Affiliation(s)
- Sheila A. Kitchen
- Department of Integrative Biology, Oregon State University, 3029 Cordley Hall, Corvallis, OR 97331, USA
| | - Virginia M. Weis
- Department of Integrative Biology, Oregon State University, 3029 Cordley Hall, Corvallis, OR 97331, USA
| |
Collapse
|
4
|
Orchestration of membrane receptor signaling by membrane lipids. Biochimie 2015; 113:111-24. [DOI: 10.1016/j.biochi.2015.04.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 04/05/2015] [Indexed: 12/20/2022]
|
5
|
Egom EEA, Mamas MA, Clark AL. The potential role of sphingolipid-mediated cell signaling in the interaction between hyperglycemia, acute myocardial infarction and heart failure. Expert Opin Ther Targets 2012; 16:791-800. [DOI: 10.1517/14728222.2012.699043] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
6
|
Ruckhäberle E, Holtrich U, Engels K, Hanker L, Gätje R, Metzler D, Karn T, Kaufmann M, Rody A. Acid ceramidase 1 expression correlates with a better prognosis in ER-positive breast cancer. Climacteric 2010; 12:502-13. [PMID: 19905902 DOI: 10.3109/13697130902939913] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVES Ceramide and sphingosine mediate response to cancer therapy, inhibit cell growth and induce apoptosis in vitro. Only a few clinical data about the impact of ceramide and sphingosine iny vivo are available. We investigated the relevance of ceramide- and sphingosine-generating enzymes in breast cancer (acid ceramidase 1 (ASAH1), ceramide synthases 4 (LASS4) and 6 (LASS6)) by means of gene expression analysis. METHODS We analyzed differences in ASAH1, LASS4 and LASS6 on mRNA level between breast cancer subgroups using microarray data from 1581 tumor samples. RESULTS High ASAH1, LASS4 and LASS6 expression correlates with pathohistological grading (p < 0.001) and estrogen receptor (ER) status (p < 0.001). High ASAH1 expression was associated with a larger tumor size >2 cm (p = 0.003), while high LASS6 expression was correlated with ErbB2 negativity (p < 0.001). In survival analysis, we detected a significant better prognosis of patients with higher ASAH1 expression (p = 0.002) in the ER-positive subgroup. In contrast, expression of LASS4 or LASS6 did not show any prognostic impact. In the multivariate analysis, only ASAH1 expression (p = 0.002), tumor size (p < 0.0001) and ErbB2 positivity (p = 0.041) remained significant. CONCLUSION ASAH1 is an estrogen-dependent member of the sphingolipid metabolism, which might provide further prognostic information in ER-positive breast cancers.
Collapse
Affiliation(s)
- E Ruckhäberle
- Departments of Obstetrics and Gynecology, J.W.Goethe-University, Frankfurt, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Satoh Y, Li X, Yokota H, Osada M, Ozaki Y, Katoh R, Yatomi Y. Regulation by Sphingolipids of the Fate of FRTL-5 Cells. J Biochem 2008; 145:31-6. [DOI: 10.1093/jb/mvn138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
8
|
Radin NS. Allylic structures in cancer drugs and body metabolites that control cell life and death. Expert Opin Drug Discov 2007; 2:809-21. [DOI: 10.1517/17460441.2.6.809] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
9
|
Karahatay S, Thomas K, Koybasi S, Senkal CE, ElOjeimy S, Liu X, Bielawski J, Day TA, Boyd Gillespie M, Sinha D, Norris JS, Hannun YA, Ogretmen B. Clinical relevance of ceramide metabolism in the pathogenesis of human head and neck squamous cell carcinoma (HNSCC): attenuation of C(18)-ceramide in HNSCC tumors correlates with lymphovascular invasion and nodal metastasis. Cancer Lett 2007; 256:101-11. [PMID: 17619081 PMCID: PMC2084356 DOI: 10.1016/j.canlet.2007.06.003] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 04/30/2007] [Accepted: 06/05/2007] [Indexed: 11/22/2022]
Abstract
It has been documented previously that defects in the generation of C(18)-ceramide, a product of ceramide synthase 1 (CerS1), also known as longevity assurance gene 1 (hLASS1), play important roles in the pathogenesis and/or progression of HNSCC. However, whether altered levels of ceramide generation in HNSCC tumors have any clinical relevance remains unknown. In this study, the levels of endogenous ceramides were measured in tumor tissues of 45 HNSCC patients as compared to their normal tissues using high-pressure liquid chromatography/mass spectrometry (LC/MS), and then possible link between ceramide levels and the clinical parameters of HNSCC were examined. The data showed that the levels of C(16)-, C(24)-, C(24:1)-ceramides were significantly elevated in the majority of tumor tissues compared to their normal tissues, while the levels of only C(18)-ceramide were significantly decreased in HNSCC tumors, especially in tumor tissues of male patients. Importantly, it was also shown here that decreased C(18)-ceramide levels in HNSCC tumor tissues were significantly associated with the higher incidences of lymphovascular invasion, and pathologic nodal metastasis. Importantly, attenuation of C(18)-ceramide was also positively linked to the higher overall stages of the primary HNSCC tumors. Therefore, these data suggest, for the first time, that the defects in the generation/accumulation of C(18)-ceramide might have important clinical roles in HNSCC, especially in lymphovascular invasion and nodal disease.
Collapse
Affiliation(s)
- Serdar Karahatay
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
- Department of Otolaryngology, Head and Surgery, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
- Gulhane Military Medical Academy, Department of Otolaryngology, Ankara, Turkey
| | - Kesha Thomas
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
| | - Serap Koybasi
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
- Department of Otolaryngology, Head and Surgery, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
| | - Can E. Senkal
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
| | - Saeed ElOjeimy
- Department of Microbiology and Immunology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
| | - Xiang Liu
- Department of Microbiology and Immunology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
| | - Jacek Bielawski
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
| | - Terry A. Day
- Department of Otolaryngology, Head and Surgery, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
- Hollings Cancer Center, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
| | - M Boyd Gillespie
- Department of Otolaryngology, Head and Surgery, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
- Hollings Cancer Center, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
| | - Debajyoti Sinha
- Hollings Cancer Center, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
- Department of Biostatistics, Bioinformatics and Epidemiology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
| | - James S. Norris
- Department of Microbiology and Immunology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
- Hollings Cancer Center, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
| | - Yusuf A. Hannun
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
- Hollings Cancer Center, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
| | - Besim Ogretmen
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
- Hollings Cancer Center, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, South Carolina, USA
- *Corresponding author. Tel.: +1 843-792-0940, Fax: +1 843-792-8568. E-mail address: (B. Ogretmen)
| |
Collapse
|
10
|
Zheng W, Kollmeyer J, Symolon H, Momin A, Munter E, Wang E, Kelly S, Allegood JC, Liu Y, Peng Q, Ramaraju H, Sullards MC, Cabot M, Merrill AH. Ceramides and other bioactive sphingolipid backbones in health and disease: lipidomic analysis, metabolism and roles in membrane structure, dynamics, signaling and autophagy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1864-84. [PMID: 17052686 DOI: 10.1016/j.bbamem.2006.08.009] [Citation(s) in RCA: 424] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Accepted: 08/16/2006] [Indexed: 12/14/2022]
Abstract
Sphingolipids are comprised of a backbone sphingoid base that may be phosphorylated, acylated, glycosylated, bridged to various headgroups through phosphodiester linkages, or otherwise modified. Organisms usually contain large numbers of sphingolipid subspecies and knowledge about the types and amounts is imperative because they influence membrane structure, interactions with the extracellular matrix and neighboring cells, vesicular traffic and the formation of specialized structures such as phagosomes and autophagosomes, as well as participate in intracellular and extracellular signaling. Fortunately, "sphingolipidomic" analysis is becoming feasible (at least for important subsets such as all of the backbone "signaling" subspecies: ceramides, ceramide 1-phosphates, sphingoid bases, sphingoid base 1-phosphates, inter alia) using mass spectrometry, and these profiles are revealing many surprises, such as that under certain conditions cells contain significant amounts of "unusual" species: N-mono-, di-, and tri-methyl-sphingoid bases (including N,N-dimethylsphingosine); 3-ketodihydroceramides; N-acetyl-sphingoid bases (C2-ceramides); and dihydroceramides, in the latter case, in very high proportions when cells are treated with the anticancer drug fenretinide (4-hydroxyphenylretinamide). The elevation of DHceramides by fenretinide is befuddling because the 4,5-trans-double bond of ceramide has been thought to be required for biological activity; however, DHceramides induce autophagy and may be important in the regulation of this important cellular process. The complexity of the sphingolipidome is hard to imagine, but one hopes that, when partnered with other systems biology approaches, the causes and consequences of the complexity will explain how these intriguing compounds are involved in almost every aspect of cell behavior and the malfunctions of many diseases.
Collapse
Affiliation(s)
- Wenjing Zheng
- School of Biology, Chemistry and Biochemistry, Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332-0230, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Abstract
Sphingomyelin used to be considered only as a structural molecule of the outer leaflet of the plasma membrane of mammalian cells. However, in the last five years it has become clear that sphingomyelin is rapidly degraded and resynthesized in a pathway that could function in signal transduction. Indeed, it is now known that this pathway plays a role in signal transduction for at least one cytokine, tumour necrosis factor alpha. It seems possible that other cell surface receptors will also utilize this pathway for signalling.
Collapse
Affiliation(s)
- R Kolesnick
- Laboratory of Signal Transduction, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
| |
Collapse
|
12
|
Won JS, Im YB, Khan M, Singh AK, Singh I. The role of neutral sphingomyelinase produced ceramide in lipopolysaccharide-mediated expression of inducible nitric oxide synthase. J Neurochem 2003; 88:583-93. [PMID: 14720208 DOI: 10.1046/j.1471-4159.2003.02165.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Lipopolysaccharide (LPS) and interferon-gamma (IFN) treatment of C6 rat glioma cells increased the intracellular ceramide level and the expression of the inducible nitric oxide synthase (iNOS) gene. To delineate the possible role of ceramide in the induction of iNOS, we examined the source of intracellular ceramide and associated signal transduction pathway(s) with the use of inhibitors of intracellular ceramide generation. The inhibitor of neutral sphingomyelinase (3-O-methylsphingomyelin, MSM) inhibited the induction of iNOS, whereas inhibitor of acidic sphingomyelinase (SR33557) or that of ceramide de novo synthesis (fumonisin B1) had no effect on the induction of iNOS. MSM-mediated inhibition of iNOS induction was reversed by the supplementation of exogenous C8-ceramide, suggesting that ceramide production by neutral sphingomyelinase (nSMase) is a key mediator in the induction of iNOS. The MSM-mediated inhibition of iNOS gene expression correlated with the decrease in the activity of ras. Inhibition of co-transfected iNOS promoter activity by dominant negative ras supported the role of ras in the nSMase-dependent regulation of iNOS gene. NF-kappaB DNA binding activity and its transactivity were also reduced by MSM pretreatment, and were completely reversed by the supplementation of C8-ceramide. As the dominant negative ras also reduced NF-kappaB transactivity, NF-kappaB activation may be downstream of ras. Our results suggest that ceramide generated by nSMase may be a critical mediator in the regulation of iNOS gene expression via ras-mediated NF-kappaB activation under inflammatory conditions.
Collapse
Affiliation(s)
- Je-Seong Won
- Developmental Neurogenetics, Department of Pediatrics, Medical University of South Carolina, Charleston 29425, USA
| | | | | | | | | |
Collapse
|
13
|
Abstract
Ceramides are the major lipid constituent of lamellar sheets present in the intercellular spaces of the stratum corneum. These lamellar sheets are thought to provide the barrier property of the epidermis. It is generally accepted that the intercellular lipid domain is composed of approximately equimolar concentrations of free fatty acids, cholesterol, and ceramides. Ceramides are a structurally heterogeneous and complex group of sphingolipids containing derivatives of sphingosine bases in amide linkage with a variety of fatty acids. Differences in chain length, type and extent of hydroxylation, saturation etc. are responsible for the heterogeneity of the epidermal sphingolipids. It is well known that ceramides play an essential role in structuring and maintaining the water permeability barrier function of the skin. In conjunction with the other stratum corneum lipids, they form ordered structures. An essential factor is the physical state of the lipid chains in the nonpolar regions of the bilayers. The stratum corneum intercellular lipid lamellae, the aliphatic chains in the ceramides and the fatty acids are mostly straight long-chain saturated compounds with a high melting point and a small polar head group. This means that at physiological temperatures, the lipid chains are mostly in a solid crystalline or gel state, which exhibits low lateral diffusional properties and is less permeable than the state of liquid crystalline membranes, which are present at higher temperatures. The link between skin disorders and changes in barrier lipid composition, especially in ceramides, is difficult to prove because of the many variables involved. However, most skin disorders that have a diminished barrier function present a decrease in total ceramide content with some differences in the ceramide pattern. Formulations containing lipids identical to those in skin and, in particular, some ceramide supplementation could improve disturbed skin conditions. Incomplete lipid mixtures yield abnormal lamellar body contents, and disorder intercellular lamellae, whereas complete lipid mixtures result in normal lamellar bodies and intercellular bilayers. The utilization of physiological lipids according to these parameters have potential as new forms of topical therapy for dermatoses. An alternative strategy to improving barrier function by topical application of the various mature lipid species is to enhance the natural lipid-synthetic capability of the epidermis through the topical delivery of lipid precursors.
Collapse
Affiliation(s)
- Luisa Coderch
- Instituto de Investigaciones Químicas y Ambientales de Barcelona, Barcelona, Spain.
| | | | | | | |
Collapse
|
14
|
Ravid T, Tsaba A, Gee P, Rasooly R, Medina EA, Goldkorn T. Ceramide accumulation precedes caspase-3 activation during apoptosis of A549 human lung adenocarcinoma cells. Am J Physiol Lung Cell Mol Physiol 2003; 284:L1082-92. [PMID: 12576296 PMCID: PMC4370276 DOI: 10.1152/ajplung.00172.2002] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ceramide, the basic structural unit of sphingolipids, controls the balance between cell growth and death by inducing apoptosis. We have previously shown that accumulation of ceramide, triggered by hydrogen peroxide (H(2)O(2)) or by short-chain ceramide analogs, induces apoptosis of lung epithelial cells. Here we elucidate the link between caspase-3 activation, at the execution phase, and ceramide accumulation, at the commitment phase of apoptosis in A549 human lung adenocarcinoma cells. The induction of ceramide accumulation by various triggers of ceramide generation, such as H(2)O(2), C(6)-ceramide, or UDP-glucose-ceramide glucosyltransferase inhibitor dl-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol, triggered the activation of caspase-3. This ceramide elevation also induced the cleavage of the death substrate poly(ADP-ribose) polymerase and was followed by apoptotic cell death. Ceramide-mediated apoptosis was blocked by a general caspase inhibitor, Boc-d-fluoromethylketone, and by overexpression of the antiapoptotic protein Bcl-2. Notably, overexpression of Bcl-2 reduced the basal cellular levels of ceramide and prevented the induction of ceramide generation by C(6)-ceramide, which implies ceramide generation as a possible target for the antiapoptotic effects of Bcl-2.
Collapse
Affiliation(s)
- Tommer Ravid
- Center for Comparative Respiratory Biology and Medicine, Department of Internal Medicine, University of California, Davis, California 95616, USA.
| | | | | | | | | | | |
Collapse
|
15
|
Zhao S, Du XY, Chen JS, Zhou YC, Song JG. Secretory Phospholipase A2 Inhibits Epidermal Growth Factor-Induced Receptor Activation. Exp Cell Res 2002; 279:354-64. [PMID: 12243760 DOI: 10.1006/excr.2002.5622] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Secretory phospholipase A(2) (sPLA(2)) plays important roles in mediating various cellular processes, including cell proliferation, differentiation, apoptosis, and inflammatory response. In this study, we demonstrated that a basic sPLA(2) inhibits epidermal growth factor (EGF)-induced EGF receptor activation, as determined by autophosphorylation of EGF receptor, EGF-activated phospholipase D (PLD) activity, and phospholipase C-gamma(1) (PLC-gamma(1)) tyrosine phosphorylation in a human epidermoid carcinoma cell line, A-431. Treatment of cells with exogenous neutral sphingomyelinase (SMase) or a cell permeable ceramide analog, C(2)-ceramide, also caused similar inhibitory effects on EGF-induced activation of EGF receptor, tyrosine phosphorylation of PLC-gamma(1), and the activation of PLD. sPLA(2)-induced inhibition of EGF receptor was associated with arachidonic acid release, which was followed by an increase in intracellular ceramide formation. Both sPLA(2) and exogenous C(2)-ceramide are able to inhibit the proliferation of A-431. The data presented indicate for the first time that sPLA(2) downregulates the EGF receptor-mediated intracellular signal transduction that may be mediated by arachidonic acid and/or ceramide.
Collapse
Affiliation(s)
- Sheng Zhao
- Laboratory of Molecular Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Box 25, 320 Yue-Yang Road, Shanghai, 200031, Peoples' Republic of China
| | | | | | | | | |
Collapse
|
16
|
Ahn EH, Schroeder JJ. Sphingoid bases and ceramide induce apoptosis in HT-29 and HCT-116 human colon cancer cells. Exp Biol Med (Maywood) 2002; 227:345-53. [PMID: 11976405 DOI: 10.1177/153537020222700507] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Complex dietary sphingolipids such as sphingomyelin and glycosphingolipids have been reported to inhibit development of colon cancer. This protective role may be the result of turnover to bioactive metabolites including sphingoid bases (sphingosine and sphinganine) and ceramide, which inhibit proliferation and stimulate apoptosis. The purpose of the present study was to investigate the effects of sphingoid bases and ceramides on the growth, death, and cell cycle of HT-29 and HCT-116 human colon cancer cells. The importance of the 4,5-trans double bond present in both sphingosine and C(2)-ceramide (a short chain analog of ceramide) was evaluated by comparing the effects of these lipids with those of sphinganine and C(2)-dihydroceramide (a short chain analog of dihydroceramide), which lack this structural feature. Sphingosine, sphinganine, and C(2)-ceramide inhibited growth and caused death of colon cancer cells in time- and concentration-dependent manners, whereas C(2)-dihydroceramide had no effect. These findings suggest that the 4,5-trans double bond is necessary for the inhibitory effects of C(2)-ceramide, but not for sphingoid bases. Evaluation of cellular morphology via fluorescence microscopy and quantitation of fragmented low-molecular weight DNA using the diphenylamine assay demonstrated that sphingoid bases and C(2)-ceramide cause chromatin and nuclear condensation as well as fragmentation of DNA, suggesting these lipids kill colon cancer cells by inducing apoptosis. Flow cytometric analyses confirmed that sphingoid bases and C(2)-ceramide increased the number of cells in the A(0) peak indicative of apoptosis and demonstrated that sphingoid bases arrest the cell cycle at G(2)/M phase and cause accumulation in the S phase. These findings establish that sphingoid bases and ceramide induce apoptosis in colon cancer cells and implicate them as potential mediators of the protective role of more complex dietary sphingolipids in colon carcinogenesis.
Collapse
Affiliation(s)
- Eun Hyun Ahn
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824-1224, USA
| | | |
Collapse
|
17
|
Smith ER, Merrill AH, Obeid LM, Hannun YA. Effects of sphingosine and other sphingolipids on protein kinase C. Methods Enzymol 2001; 312:361-73. [PMID: 11070884 DOI: 10.1016/s0076-6879(00)12921-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- E R Smith
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322-3050, USA
| | | | | | | |
Collapse
|
18
|
Radin NS. Killing cancer cells by poly-drug elevation of ceramide levels: a hypothesis whose time has come? EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:193-204. [PMID: 11168352 DOI: 10.1046/j.1432-1033.2001.01845.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Many papers have shown that sphingolipids control the balance in cells between growth and proliferation, and cell death by apoptosis. Sphingosine-1-phosphate (Sph1P) and glucosylceramide (GlcCer) induce proliferation processes, and ceramide (Cer), a metabolic intermediate between the two, induces apoptosis. In cancers, the balance seems to have come undone and it should be possible to kill the cells by enhancing the processes that lead to ceramide accumulation. The two control systems are intertwined, modulated by a variety of agents affecting the activities of the enzymes in Cer-GlcCer-Sph1P interdependence. It is proposed that successful cancer chemotherapy requires the use of many agents to elevate ceramide levels adequately. This review updates current knowledge of sphingolipid metabolism and some of the evidence showing that ceramide plays a causal role in apoptosis induction, as well as a chemotherapeutic agent.
Collapse
Affiliation(s)
- N S Radin
- Mental Health Research Institute, University of Michigan, Ann Arbor, MI, USA.
| |
Collapse
|
19
|
Goldkorn T. Ceramide generation and apoptosis in autoimmunity. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1529-1049(01)00011-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
20
|
Abstract
A significant corpus of work over the last decade has firmly established an important role for sphingolipids in a variety of important biological processes. Such processes include signaling events related to cell growth, differentiation, programmed cell death, and stress responses. These processes not only involve those sphingolipids that accumulate as a result of a variety of inherited lysosomal storage disorders, but, in addition, sphingolipids associated with long-chain base metabolism. This article reviews the chemical properties, pathways, regulated metabolism, and signaling function of sphingolipids. In addition, the potential roles of sphingolipids in renal-specific processes are considered. While a variety of cellular functions have been ascribed to sphingolipids, in many cases proof of the concept has yet to be well established. Thus, a number of critical questions can be posed in interpreting these studies. Several of these questions are considered.
Collapse
Affiliation(s)
- J A Shayman
- Nephrology Division, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0676, USA.
| |
Collapse
|
21
|
Meuillet EJ, Mania-Farnell B, George D, Inokuchi JI, Bremer EG. Modulation of EGF receptor activity by changes in the GM3 content in a human epidermoid carcinoma cell line, A431. Exp Cell Res 2000; 256:74-82. [PMID: 10739654 DOI: 10.1006/excr.1999.4509] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gangliosides have been described as modulators of growth factor receptors. For example, GM3 addition in cell culture medium inhibits epidermal growth factor (EGF)-stimulated receptor autophosphorylation. Furthermore, depletion of ganglioside by sialidase gene transfection appeared to increase EGF receptor (EGFR) autophosphorylation. These data suggested that changes in GM3 content may result in different responses to EGF. In this study, the ceramide analog d-threo-1-phenyl-2-decannoylamino-3-morpholino-1-propanol ([D]-PDMP), which inhibits UDP-glucose-ceramide glucosyltransferase, and addition of GM3 to the culture medium were used to study the effects of GM3 on the EGFR. Addition of 10 microM [D]-PDMP to A431 cells resulted in significant GM3 depletion. Additionally, EGFR autophosphorylation was increased after EGF stimulation. When exogenous GM3 was added in combination with [D]-PDMP, the enhanced EGFR autophosphorylation was returned to control levels. [D]-PDMP also increased EGF-induced cell proliferation, consistent with its effect on autophosphorylation. Once again, the addition of GM3 in combination with [D]-PDMP reversed these effects. These results indicate that growth factor receptor functions can be modulated by the level of ganglioside expression in cell lines. Addition of GM3 inhibits EGFR activity and decrease of GM3 levels using [D]-PDMP treatment enhances EGFR activity. Modulation of growth factor receptor function may provide an explanation for how transformation-dependent ganglioside changes contribute to the transformed phenotype.
Collapse
Affiliation(s)
- E J Meuillet
- The Brain Tumor Research Program, Children's Memorial Medical Center, Chicago, Illinois 60614, USA
| | | | | | | | | |
Collapse
|
22
|
Abstract
Lung epithelium plays a significant role in modulating the inflammatory response to lung injury. Airway epithelial cells are targeted by hydrogen peroxide (H(2)O(2)) and oxygen radicals, which are agents commonly produced during inflammatory processes. The mechanisms and molecular sites affected by H(2)O(2) are largely unknown but may involve the induction of sphingomyelin (SM) hydrolysis to generate ceramide, which serves as a second messenger in initiating an apoptotic response. Here we show that exposure of human airway epithelial (HAE) cells to 50 to 100 microM H(2)O(2) induces within 5 to 10 min a greater than 2-fold activation of neutral sphingomyelinase activity with concomitant SM hydrolysis, ceramide generation, and apoptosis. On the other hand, activation of protein kinase C (PKC) by 12-O-tetradecanoylphorbol-13-acetate inhibits both H(2)O(2)-induced ceramide production and apoptosis. The apoptotic response could be restored by the addition of 25 microM cell-permeant C6-ceramide. These findings indicate that ceramide, the product of SM hydrolysis, plays an important role in H(2)O(2)-induced apoptosis in HAE cells, and that PKC counteracts ceramide-mediated apoptosis in these cells. We suggest that the mediation of epithelial cell apoptosis by ceramide and its inhibition by PKC constitute a central mechanism by which inflammatory processes are modulated in the epithelium of the lung.
Collapse
Affiliation(s)
- C Chan
- Signal Transduction, Department of Medicine, University of California Davis School of Medicine, Davis, CA 95616, USA
| | | |
Collapse
|
23
|
Murthy S, Mathur SN, Field FJ. Tumor necrosis factor-alpha and interleukin-1beta inhibit apolipoprotein B secretion in CaCo-2 cells via the epidermal growth factor receptor signaling pathway. J Biol Chem 2000; 275:9222-9. [PMID: 10734059 DOI: 10.1074/jbc.275.13.9222] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In inflammatory conditions of the gut, cytokines are released into the mucosa and submucosa propagating and sustaining the inflammatory response. In CaCo-2 cells, we have shown that various inflammatory cytokines interfere with the secretion of lipids, an effect that is likely caused by the release of a ligand to the epidermal growth factor (EGF) receptor. In the present study, the role of the EGF receptor signaling pathway and the effects of the cytokines tumor necrosis factor-alpha (TNF-alpha) and and interleukin 1beta (IL-1beta) on triacylglycerol-rich lipoprotein secretion were investigated. CaCo-2 cells were incubated with oleic acid to enhance triacylglycerol-rich lipoprotein secretion. TNF-alpha and IL-1beta significantly decreased the basolateral secretion of apolipoprotein B (apoB) mass, with IL-1beta being more potent. Tyrphostin, an inhibitor of the EGF receptor intrinsic tryosine kinase, prevented or markedly attenuated the decrease in apoB secretion by TNF-alpha or IL-1beta. Both cytokines increased the phosphorylation of the EGF receptor by 30 min. Moreover, phosphotyrosine immunoblots of the EGF receptor demonstrated an increase in tyrosine residues phosphorylated by 0.5 and 6.5 h. At both these time points, TNF-alpha and IL-1beta also decreased the binding of EGF to its cell surface receptor. At 6.5 h, activation of the EGF receptor was sustained. In contrast, the early activation of the receptor was only transient as receptor phosphorylation and binding of EGF to its receptor returned to basal levels by 2 h. Preventing ligand binding to the EGF receptor by a receptor-blocking antibody attenuated receptor activation observed after 6.5 h. This did not occur at 0.5 h, suggesting that early activation of the EGF receptor was non-ligand-mediated. Similarly, apoB secretion was inhibited by an early non-ligand-mediated process; whereas at the later time, inhibition of apoB secretion was ligand-mediated. Thus, the inflammatory cytokines TNF-alpha and IL-1beta interfere with the secretion of triacylglycerol-rich lipoproteins by both early and delayed signaling events mediated by the EGF receptor signaling pathway.
Collapse
Affiliation(s)
- S Murthy
- Department of Internal Medicine and Veterans Affairs, University of Iowa, Iowa City, Iowa 52242, USA.
| | | | | |
Collapse
|
24
|
Nair P, Tammariello SP, Estus S. Ceramide selectively inhibits apoptosis-associated events in NGF-deprived sympathetic neurons. Cell Death Differ 2000; 7:207-14. [PMID: 10713735 DOI: 10.1038/sj.cdd.4400628] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Ceramide manifests both neurotoxic and neuroprotective properties depending on the experimental system. Ito and Horigome previously reported that ceramide delays apoptosis in a classic model of developmental programmed cell death, i.e. sympathetic neurons undergoing NGF deprivation.1 Here, we investigated the actions of ceramide upon the biochemical and genetic changes that occur in NGF deprived neurons. We correlate ceramide's neuroprotective actions with the ability of ceramide to antagonize NGF deprivation-induced oxidative stress and c-jun induction, both of which contribute to apoptosis in this model. However, ceramide did not block NGF deprivation-induced declines in RNA and protein synthesis, suggesting that ceramide does not slow all apoptosis-related events. Overall, these results are significant in that they show that ceramide acts early in the death cascade to antagonize two events necessary for NGF-deprivation induced neuronal apoptosis. Moreover, these results dissociate declines in neuronal function, i.e. macromolecular synthesis, from the neuronal death cascade.
Collapse
Affiliation(s)
- P Nair
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, KY 40536, USA
| | | | | |
Collapse
|
25
|
Liu G, Kleine L, Hébert RL. Advances in the signal transduction of ceramide and related sphingolipids. Crit Rev Clin Lab Sci 1999; 36:511-73. [PMID: 10656539 DOI: 10.1080/10408369991239240] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Recently, the sphingolipid metabolites ceramide, sphingosine, ceramide 1-P, and sphingosine 1-P have been implicated as second messengers involved in many different cellular functions. Publications on this topic are appearing at a rapidly increasing rate and new developments in this field are also appearing rapidly. It is thus important to summarize the results obtained from many different laboratories and from different fields of research to obtain a clearer picture of the importance of sphingolipid metabolites. This article reviews the studies from the last few years and includes the effects of a variety of extracellular agents on sphingolipid signal transduction pathways in different tissues and cells and on the mechanisms of regulation. Sphingomyelin exists in a number of functionally distinct pools and is composed of distinct molecular species. Sphingomyelin metabolites may be formed by many different pathways. For example, the generation of ceramide from sphingomyelin can be catalyzed by at least five different sphingomyelinases. A large variety of stimuli can induce the generation of ceramide, leading to activation or inhibition of various cellular events such as proliferation, differentiation, apoptosis, and inflammation. The effect of ceramide on these physiological processes is due to its many different downstream targets. It can activate ceramide-activated protein kinases and ceramide-activated protein phosphatases. It also activates or inhibits PKCs, PLD, PLA2, PC-PLC, nitric oxide synthase, and the ERK and SAPK/JNK signaling cascades. Ceramide activates or inhibits transcription factors, modulates calcium homeostasis and interacts with the retinoblastoma protein to regulate cell cycle progression. Most of the work in this field has involved the study of ceramide effects, but the roles of the other three sphingomyelin metabolites is now attracting much attention. The complex interactions between signaling components and ceramide and the controls regulating these interactions are now being identified and are presented in this review.
Collapse
Affiliation(s)
- G Liu
- Department of Cellular and Molecular Medicine, University of Ottawa, Ontario, Canada
| | | | | |
Collapse
|
26
|
Yang L, Yatomi Y, Miura Y, Satoh K, Ozaki Y. Metabolism and functional effects of sphingolipids in blood cells. Br J Haematol 1999; 107:282-93. [PMID: 10583213 DOI: 10.1046/j.1365-2141.1999.01697.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We examined the sphingolipid metabolism of peripheral blood cells, i. e. platelets, erythrocytes, neutrophils and mononuclear cells. A distinguishing characteristic of sphingolipid metabolism in these highly differentiated cells was their high sphingosine (Sph) kinase activity. The occurrence of [3H]sphingosine 1-phosphate (Sph-1-P) from [3H]Sph (actively incorporated from the outside) in the blood cells was strong, long-lasting, and independent of cell activation. Hence, the possibility of Sph-1-P playing a second messenger role is remote in these cells. About 40% of platelet Sph-1-P could be released extracellularly by 12-O-tetradecanoylphorbol 13-acetate, possibly through mediation by protein kinase C. On the other hand, in erythrocytes, neutrophils and mononuclear cells a significant percentage of Sph-1-P formed inside the cell was discharged without stimulation, whereas the stimulation-dependent release was marginal. In contrast to active [3H]Sph conversion to [3H]Sph-1-P, formation of [3H]sphingomyelin was barely detectable in the blood cells; this was especially true for anucleate platelets and erythrocytes. The Sph --> Sph-1-P pathway may become predominant over the Sph --> Cer --> sphingomyelin pathway during late-stage differentiation into platelets or erythrocytes. Sph and its methylated derivative, N, N-dimethylsphingosine, induced apoptosis not only in neutrophils but also in mononuclear cells, whereas Sph-1-P elicited Ca2+ mobilization in platelets. Our results suggest that all blood cells may remove plasma Sph, which is harmful or suppressive to cellular functions, and change it into Sph-1-P, acting as the source of plasma Sph-1-P, which may play a variety of important roles in blood vessels.
Collapse
Affiliation(s)
- L Yang
- Department of Laboratory Medicine, Yamanashi Medical University, Nakakoma, Yamanashi, Japan
| | | | | | | | | |
Collapse
|
27
|
Waggoner DW, Xu J, Singh I, Jasinska R, Zhang QX, Brindley DN. Structural organization of mammalian lipid phosphate phosphatases: implications for signal transduction. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1439:299-316. [PMID: 10425403 DOI: 10.1016/s1388-1981(99)00102-x] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
This article describes the regulation of cell signaling by lipid phosphate phosphatases (LPPs) that control the conversion of bioactive lipid phosphates to their dephosphorylated counterparts. A structural model of the LPPs, that were previously called Type 2 phosphatidate phosphatases, is described. LPPs are characterized by having no Mg(2+) requirement and their insensitivity to inhibition by N-ethylmaleimide. The LPPs have six putative transmembrane domains and three highly conserved domains that define a phosphatase superfamily. The conserved domains are juxtaposed to the proposed membrane spanning domains such that they probably form the active sites of the phosphatases. It is predicted that the active sites of the LPPs are exposed at the cell surface or on the luminal surface of intracellular organelles, such as Golgi or the endoplasmic reticulum, depending where various LPPs are expressed. LPPs could attenuate cell activation by dephosphorylating bioactive lipid phosphate esters such as phosphatidate, lysophosphatidate, sphingosine 1-phosphate and ceramide 1-phosphate. In so doing, the LPPs could generate alternative signals from diacylglycerol, sphingosine and ceramide. The LPPs might help to modulate cell signaling by the phospholipase D pathway. For example, phosphatidate generated within the cell by phospholipase D could be converted by an LPP to diacylglycerol. This should change the relative balance of signaling by these two lipids. Another possible function of the LPPs relates to the secretion of lysophosphatidate and sphingosine 1-phosphate by activated platelets and other cells. These exogenous lipids activate phospholipid growth factor receptors on the surface of cells. LPP activities could attenuate cell activation by lysophosphatidate and sphingosine 1-phosphate through their respective receptors.
Collapse
Affiliation(s)
- D W Waggoner
- Department of Biochemistry (Signal Transduction Laboratories), Lipid and Lipoprotein Research Group, University of Alberta, 357 Heritage Medical Research Centre, Edmonton, Alberta T6G 2S2, Canada
| | | | | | | | | | | |
Collapse
|
28
|
Ghidoni R, Sala G, Giuliani A. Use of sphingolipid analogs: benefits and risks. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1439:17-39. [PMID: 10395962 DOI: 10.1016/s1388-1981(99)00074-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- R Ghidoni
- INSERM U410, Neuroendocrinologie et Biologie Cellulaire Digestives, Faculté de Médecine Xavier Bichat, Paris, France.
| | | | | |
Collapse
|
29
|
Goldkorn T, Balaban N, Matsukuma K, Chea V, Gould R, Last J, Chan C, Chavez C. EGF-Receptor phosphorylation and signaling are targeted by H2O2 redox stress. Am J Respir Cell Mol Biol 1998; 19:786-98. [PMID: 9806743 DOI: 10.1165/ajrcmb.19.5.3249] [Citation(s) in RCA: 154] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Inflammation of the respiratory tract is associated with the production of reactive oxygen species, such as hydrogen peroxide (H2O2) and superoxide (O2-), which contribute extensively to lung injury in diseases of the respiratory tract. The mechanisms and target molecules of these oxidants are mainly unknown but may involve modifications of growth-factor receptors. We have shown that H2O2 induces epidermal growth factor (EGF)-receptor tyrosine phosphorylation in intact cells as well as in membranes of A549 lung epithelial cells. On the whole, total phosphorylation of the EGF receptor induced by H2O2 was lower than that induced by the ligand EGF. Phosphorylation was confined to tyrosine residues and was inhibited by addition of genistein, indicating that it was due to the activation of protein tyrosine kinase (PTK). Phosphoamino acid analysis revealed that although the ligand, EGF, enhanced the phosphorylation of serine, threonine, and tyrosine residues, H2O2 preferentially enhanced tyrosine phosphorylation of the EGF receptor. Serine and threonine phosphorylation did not occur, and the turnover rate of the EGF receptor was slower after H2O2 exposure. Selective H2O2-mediated phosphorylation of tyrosine residues on the EGF receptor was sufficient to activate phosphorylation of an SH2-group-bearing substrate, phospholipase C-gamma (PLC-gamma), but did not increase mitogen-activated protein (MAP) kinase activity. Moreover, H2O2 exposure decreased protein kinase C (PKC)-alpha activity by causing translocation of PKC-alpha from the membrane to the cytoplasm. These studies provide novel insights into the capacity of a reactive oxidant, such as H2O2, to modulate EGF-receptor function and its downstream signaling. The H2O2-induced increase in tyrosine phosphorylation of the EGF receptor, and the receptor's slower rate of turnover and altered downstream phosphorylation signals may represent a mechanism by which EGF-receptor signaling can be modulated during inflammatory processes, thereby affecting cell proliferation and thus having implications in wound repair or tumor formation.
Collapse
Affiliation(s)
- T Goldkorn
- Department of Medicine, University of California, Davis School of Medicine, Davis, California, USA
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Goldkorn T, Balaban N, Shannon M, Chea V, Matsukuma K, Gilchrist D, Wang H, Chan C. H2O2 acts on cellular membranes to generate ceramide signaling and initiate apoptosis in tracheobronchial epithelial cells. J Cell Sci 1998; 111 ( Pt 21):3209-20. [PMID: 9763515 DOI: 10.1242/jcs.111.21.3209] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Hydrogen peroxide (H2O2) is an inflammatory oxidant which contributes to the pathogenesis of chronic diseases such as lung injury of the respiratory tract, atherosclerosis and cancer. The mechanisms and target sites of this reactive oxidant are mainly unknown. So far there are opposing reports as to whether reactive oxidants inhibit or promote apoptosis. We activated the death pathway in primary tracheobronchial epithelial (TBE) cells with H2O2 (20–200 microM) and observed the morphological changes, DNA laddering patterns, and DNA fragmentation associated with apoptosis. Elevation of ceramide with exogenous ceramide analogs was sufficient for apoptosis induction with the same characteristics and in the same time frame. H2O2 induced rapid sphingomyelin hydrolysis to ceramide, the elevation of which paralleled the induction of apoptosis. Furthermore, H2O2 acted directly on TBE cells membrane preparations devoid of nuclei, stimulating sphingomyelin hydrolysis through a neutral Mg2+ dependent sphingomyelinase (SMase). These data suggest that the formation of ceramide from sphingomyelin in the plasma membrane is a key event in H2O2-induced apoptosis in tracheobronchial epithelial cells.
Collapse
Affiliation(s)
- T Goldkorn
- Respiratory Signal Transduction, Department of Medicine, University of California, Davis School of Medicine, Davis, CA 95616, USA
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Lochhead KM, Zager RA. Fluorinated anesthetic exposure "activates" the renal cortical sphingomyelinase cascade. Kidney Int 1998; 54:373-81. [PMID: 9690203 DOI: 10.1046/j.1523-1755.1998.00022.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Previous studies indicate that fluorinated anesthetics can enhance sphingomyelin (SM) hydrolysis in in vitro neuronal extracts. Renal cortex has substantial SM content. Hence, this study assessed whether in vivo fluorinated anesthetic use stimulates renal SM hydrolysis, causing accumulation of ceramide, an important signaling molecule. METHODS Mice were anesthetized with isoflurane or desflurane (fluorinated anesthetics). Pentobarbital anesthetized mice served as controls. After six hours, kidney cortex was assayed for ceramide. In selected experiments, renal cortical sphingosine and sphingomyelinase (SMase) levels were also determined. Isoflurane's effects on ceramide levels in cultured human proximal tubule (HK-2) cells/isolated mouse proximal tubule segments (PTS), and on in vitro 14C-SM hydrolysis were also assessed. RESULTS Isoflurane and desflurane, but not pentobarbital, increased renal cortical ceramide levels (such as, 65% with isoflurane, P < 0.003). Isoflurane also raised PTS/HK-2 ceramide levels (by 25 to 35%). Ceramidase inhibition (fumonisin B1) did not block this ceramide accumulation in HK-2 cells. Isoflurane did not increase renal cortical/PTS SMase levels. However, it directly enhanced the ability of (acidic) SMase to effect in vitro 14C-SM hydrolysis. Isoflurane raised renal cortical sphingosine (and not just ceramide) levels, implying ongoing ceramidase activity. CONCLUSIONS Fluorinated anesthetics can stimulate renal cortical/tubule ceramide expression, presumably by stimulating SMase-mediated SM hydrolysis. Since ceramide is a potential mediator of tubule apoptosis/necrosis, these findings have potential relevance for the development of intra/post-operative acute renal failure.
Collapse
Affiliation(s)
- K M Lochhead
- Department of Medicine, University of Washington, Seattle, USA
| | | |
Collapse
|
32
|
David TS, Ortiz PA, Smith TR, Turinsky J. Sphingomyelinase has an insulin-like effect on glucose transporter translocation in adipocytes. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:R1446-53. [PMID: 9612413 DOI: 10.1152/ajpregu.1998.274.5.r1446] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Rat epididymal adipocytes were incubated with 0, 0.1, and 1 mU sphingomyelinase/ml for 30 or 60 min, and glucose uptake and GLUT-1 and GLUT-4 translocation were assessed. Adipocytes exposed to 1 mU sphingomyelinase/ml exhibited a 173% increase in glucose uptake. Sphingomyelinase had no effect on the abundance of GLUT-1 in the plasma membrane of adipocytes. In contrast, 1 mU sphingomyelinase/ml increased plasma membrane content of GLUT-4 by 120% and produced a simultaneous decrease in GLUT-4 abundance in the low-density microsomal fraction. Sphingomyelinase had no effect on tyrosine phosphorylation of either the insulin receptor beta-subunit or the insulin receptor substrate-1, a signaling molecule in the insulin signaling pathway. It is concluded that the incubation of adipocytes with sphingomyelinase results in insulin-like translocation of GLUT-4 to the plasma membrane and that this translocation does not occur via the activation of the initial components of the insulin signaling pathway.
Collapse
Affiliation(s)
- T S David
- Department of Physiology and Cell Biology, Albany Medical College, New York 12208, USA
| | | | | | | |
Collapse
|
33
|
Goldkorn T, Ding T. The rise and fall of ceramide and 1,2-diacylglycerol (DAG): modulation by transforming growth factor-beta 1 (TGF beta 1) and by epidermal growth factor (EGF). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1998; 400A:461-72. [PMID: 9547591 DOI: 10.1007/978-1-4615-5325-0_62] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Transforming growth factor beta 1 (TGF beta 1) increases the phosphorylation of the epidermal growth factor (EGF) receptor and inhibits the growth of A431 cells, but the mechanism of TGF beta 1 signaling is unknown. Recent studies from this and other laboratories suggest a novel sphingomyelin signal transduction pathway (1-4). Ceramide, which is generated by sphingomyelinase action, can be deacylated to sphingoid bases, which are potential inhibitors of protein kinase C (PKC). Ceramide appears to have bioeffector properties. Cell-permeable ceramide analogs stimulate monocytic differentiation of human leukemia (HL60) cells (1), as well as the phosphorylation of the EGF receptor at Thr669 in A431 human epidermoid carcinoma cells (2). Further studies (3,4) demonstrate the existence of a ceramide-activated protein kinase (CAPK) that may mediate some of these aspects. The present studies aim to investigate the mechanism of TGF beta 1 signaling and to explore whether TGF beta 1's pathway involves activation of PKC by 1,2-Diacylglycerol (DAG) and/or stimulation of a CAPK by ceramide. Ceramide and DAG levels of A431 cells are determined by thin layer chromatography (TLC) after treatment with either TGF beta 1 or with EGF. 100 pM TGF beta 1 treatment for 1 hr increases the cellular contents of DAG 2-fold. 20 nM EGF treatment for 15 min decreases it 0.5-fold. Ceramide levels are reduced 2-fold by TGF beta 1 and almost unaffected by EGF. To evaluate the involvement of other components of signal transduction, the effects of TGF beta 1 and EGF on PKC activity are studied. 20 nM EGF decreases membrane PKC activity to 0.5-fold of controls, whereas 100 pM TGF beta 1 treatment of A431 cells increases this activity 4-fold. Modulation of PKC activity is paralled by translocation of the enzyme between the cytosol and the membrane as determined by Western immunoblot analysis. These studies suggest that TGF beta 1 and EGF may have regulatory effects on both sphingolipid and phospholipid metabolisms which could transmodulate both the CAPK and the PKC mediated signal tranduction pathways.
Collapse
Affiliation(s)
- T Goldkorn
- Yale School of Medicine, New Haven, CT 06510, USA
| | | |
Collapse
|
34
|
Ariga T, Jarvis WD, Yu RK. Role of sphingolipid-mediated cell death in neurodegenerative diseases. J Lipid Res 1998. [DOI: 10.1016/s0022-2275(20)34198-5] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
|
35
|
Jarvis WD, Fornari FA, Auer KL, Freemerman AJ, Szabo E, Birrer MJ, Johnson CR, Barbour SE, Dent P, Grant S. Coordinate regulation of stress- and mitogen-activated protein kinases in the apoptotic actions of ceramide and sphingosine. Mol Pharmacol 1997; 52:935-47. [PMID: 9415703 DOI: 10.1124/mol.52.6.935] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We characterized participation of the stress-activated protein kinase (SAPK) cascade in the lethal actions of the cytotoxic lipid messengers ceramide and sphingosine in U937 human monoblastic leukemia cells. Acute exposure of U937 cells to either lipid resulted in loss of proliferative capacity, degradation of genomic DNA, and manifestation of apoptotic cytoarchitecture. Ceramide robustly stimulated p46-JNK1/p54-JNK2 activity and increased expression of c-jun mRNA and c-Jun protein; in contrast, sphingosine moderately stimulated p46-JNK1/p54-JNK2 and failed to modify c-jun/c-Jun expression. Dominant-negative blockade of normal c-Jun activity by transfection with the TAM-67 c-Jun NH2-terminal deletion mutant abolished the lethal actions of ceramide but was without effect on those of sphingosine, indicating that ceramide-related apoptosis is directly dependent on activation of c-Jun, whereas sphingosine-induced cell death proceeds via an unrelated downstream mechanism. Characterization of the mitogen-activated protein kinase (MAPK) cascade in these responses revealed a further functional disparity between the two lipids: basal p42-ERK1/ p44-ERK2 activity was gradually reduced by ceramide but immediately and completely suppressed by sphingosine. Moreover, blockade of the MAPK cascade by the aminomethoxyflavone MEK1 inhibitor PD-98059 unexpectedly activated p46-JNK1/p54-JNK2 and induced apoptosis in a manner qualitatively resembling that of sphingosine. Both lipids sharply increased p38-RK activity; selective pharmacological inhibition of p38-RK by the pyridinyl imidazole SB-203580 failed to mitigate the cytotoxicity associated with either ceramide or sphingosine, suggesting that p38-RK is not essential for lipid-induced apoptosis. These findings demonstrate that reciprocal alterations in the SAPK and MAPK cascades are associated with the apoptotic influence of either lipid inasmuch as (i) ceramide-mediated lethality is primarily associated with strong stimulation of SAPK and weak inhibition of MAPK, whereas (ii) sphingosine-mediated lethality is primarily associated with weak stimulation of SAPK and strong inhibition of MAPK. We therefore propose that leukemic cell survival depends on the maintenance of an imbalance of the outputs from the MAPK and SAPK systems such that the dominant basal influence of the MAPK cascade allows sustained proliferation, whereas acute redirection of this balance toward the SAPK cascade initiates apoptotic cell death.
Collapse
Affiliation(s)
- W D Jarvis
- Department of Medicine, Medical College of Virginia, Richmond 23298, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Abstract
Hepatic P450 activities are profoundly affected by various infectious and inflammatory stimuli, and this has clinical and toxicological consequences. Whereas the expression of most P450s in the liver is suppressed, some are induced. Many of the effects observed in vivo can be mimicked by pro-inflammatory cytokines and IFNs, and P450s are differentially regulated by these agents. Therefore, different cytokine profiles and concentrations in the vicinity of the hepatocyte in different models of inflammation may result in qualitatively and quantitatively different effects on populations of P450s. In addition to cytokines, glucocorticoids may have an important role in P450 regulation in stress conditions, including that caused by inflammatory stimuli. Although in many cases the decreases in activity are due primarily to a down-regulation of P450 gene transcription, it is likely that modulation of RNA and protein turnover, as well as enzyme inhibition, contributes to some of the observed effects. The mechanisms whereby these effects are produced may also vary with both the P450 under study and the time course of the effect. The complexity of the P450 response to inflammation and infection means that all of the above factors must be considered when trying to predict the effect of a given infectious or inflammatory condition on the clinical or toxic response of humans or animals to an administered drug or toxin. The question of whether the down-regulation of the hepatic P450 system to inflammation or infection is a homeostatic or pathological response cannot be answered at present. It is difficult to discern the physiological benefit of reducing hepatic P450 activities, unless it is to prevent the generation of reactive oxygen species generated by uncoupled catalytic turnover of the enzymes. On the other hand, as we proposed some years ago [64], the suppression of P450 may be due to the liver's need to utilize its transcriptional machinery and energy for the synthesis of APPs involved in the inflammatory response. In that case, one could ask why the organism has gone to the trouble of employing differential mechanisms for suppression of P450. One answer could be that the response evolved after the divergence of many of the P450 genes, necessitating the evolution of multiple redundant mechanisms for P450 suppression. In contrast to the down-regulation of P450s in the liver, the induction of several forms in this and other tissues suggests a more specific homeostatic role of these effects, e.g., in generation or catabolism of bioactive metabolites.
Collapse
Affiliation(s)
- E T Morgan
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| |
Collapse
|
37
|
Goldkorn T, Balaban N, Shannon M, Matsukuma K. EGF receptor phosphorylation is affected by ionizing radiation. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1358:289-99. [PMID: 9366260 DOI: 10.1016/s0167-4889(97)00063-3] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Eukaryotic cells respond to ionizing radiation with cell cycle arrest, activation of DNA repair mechanisms, and lethality. However, little is known about the molecular mechanisms that constitute these responses. Here we report that ionizing radiation enhances epidermal growth factor (EGF) receptor tyrosine phosphorylation in intact cells as well as in isolated membranes of A431 cells. Phosphoamino acid analysis revealed that ionizing radiation preferentially enhances tyrosine phosphorylation, while EGF enhances the phosphorylation of all three phosphoamino acids (serine, threonine and tyrosine) of the EGF receptor. In addition, radiation reduces the turnover rate of the EGF receptor, while EGF increases the rate of the receptor turnover and down-regulation. Moreover, the confined radiation-induced phosphorylation of tyrosine residues is inhibited by genistein, indicating that this phosphorylation of EGF receptor is due to protein tyrosine kinase activation. These studies provide novel insights into the capacity of radiation to modulate EGF receptor phosphorylation and function. The radiation-induced elevation in the EGF receptor tyrosine phosphorylation and the receptor's slower rate of turnover are discussed in terms of their possible role in cell growth and apoptosis modulation.
Collapse
Affiliation(s)
- T Goldkorn
- Department of Medicine, University of California, Davis School of Medicine, 95616, USA
| | | | | | | |
Collapse
|
38
|
Riboni L, Viani P, Bassi R, Prinetti A, Tettamanti G. The role of sphingolipids in the process of signal transduction. Prog Lipid Res 1997; 36:153-95. [PMID: 9624426 DOI: 10.1016/s0163-7827(97)00008-8] [Citation(s) in RCA: 150] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- L Riboni
- Department of Medical Chemistry and Biochemistry, Medical Faculty, University of Milan, Italy
| | | | | | | | | |
Collapse
|
39
|
de Chaves EI, Bussière M, Vance DE, Campenot RB, Vance JE. Elevation of ceramide within distal neurites inhibits neurite growth in cultured rat sympathetic neurons. J Biol Chem 1997; 272:3028-35. [PMID: 9006952 DOI: 10.1074/jbc.272.5.3028] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Sphingolipids are abundant constituents of neuronal membranes and have been implicated in intracellular signaling. We show that two analogs of glycosphingolipid biosynthetic intermediates, fumonisin B1 (which inhibits dihydroceramide synthesis) and DL-1-phenyl-2-palmitoylamino-3-morpholino-1-propanol (PPMP) (which inhibits glucosylceramide synthesis) decrease glycosphingolipid synthesis in rat sympathetic neurons. Although both fumonisin and PPMP inhibit glycosphingolipid synthesis, these inhibitors have differential effects on ceramide metabolism in axons. threo-PPMP, but not erythro-PPMP or fumonisin, induces an accumulation of [3H]palmitate-labeled ceramide and impairs axonal growth. Moreover, exogenously added, cell-permeable C6-ceramide, but not C6-dihydroceramide, mimicks the effect of PPMP. Our studies suggest that the lipid second messenger ceramide acts in distal axons, but not cell bodies, as a negative regulator of neurite growth.
Collapse
Affiliation(s)
- E I de Chaves
- Lipid and Lipoprotein Research Group, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada
| | | | | | | | | |
Collapse
|
40
|
Abousalham A, Liossis C, O'Brien L, Brindley DN. Cell-permeable ceramides prevent the activation of phospholipase D by ADP-ribosylation factor and RhoA. J Biol Chem 1997; 272:1069-75. [PMID: 8995404 DOI: 10.1074/jbc.272.2.1069] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The mechanism of inhibition of phospholipase D (PLD) by ceramides was determined using granulocytes differentiated from human promyelocytic leukemic (HL-60) cells. In a cell-free system, hydrolysis of phosphatidylcholine by membrane-bound PLD depended upon phosphatidylinositol 4,5-bisphosphate, guanosine 5'-3-O-(thio)triphosphate) (GTPgammaS), and cytosolic factors including ADP-ribosylating factor (ARF) and RhoA. C2-(N-acetyl-), C8- (N-octanoyl-), and long-chain ceramides, but not dihydro-C2-ceramide, inhibited PLD activity. Apyrase or okadaic acid did not modify the inhibition of PLD by ceramides, indicating that the effect in the cell-free system was unlikely to be dependent upon a ceramide-stimulated kinase or phosphoprotein phosphatases. C2- and C8-ceramides prevented the GTPgammaS-induced translocation of ARF1 and RhoA from the cytosol to the membrane fraction. In whole cells, C2-ceramide, but not dihydro-C2-ceramide, inhibited the stimulation of PLD by N-formylmethionylleucylphenylalanine and decreased the amounts of ARF1, RhoA, CDC42, Rab4, and protein kinase C-alpha and -beta1 that were associated with the membrane fraction, but did not alter the distribution of protein kinase C-epsilon and -zeta. It is concluded that one mechanism by which ceramides prevent the activation of PLD is inhibition of the translocation to membranes of G-proteins and protein kinase C isoforms that are required for PLD activity.
Collapse
Affiliation(s)
- A Abousalham
- Department of Biochemistry (Signal Transduction Laboratories), University of Alberta, Edmonton, Canada
| | | | | | | |
Collapse
|
41
|
The sphingomyelin cycle: The flip side of the lipid signaling paradigm. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s1874-5245(97)80008-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
|
42
|
Hayashi K, Nagamatsu T, Honda S, Suzuki Y. Butein (3,4,2',4'-tetrahydroxychalcone) ameliorates experimental anti-glomerular basement membrane antibody-associated glomerulonephritis (3). Eur J Pharmacol 1996; 316:297-306. [PMID: 8982701 DOI: 10.1016/s0014-2999(96)00689-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The antinephritic effects of butein (3,4,2',4'-tetrahydroxychalcone) on original-type anti-glomerular basement membrane antibody-associated glomerulonephritis in rats were investigated. Butein was given to anti-glomerular basement membrane antibody-associated glomerulonephritic rats for 15 days after the induction of nephritis. Butein prevented proteinuria and histological alterations. The up-regulation of intercellular adhesion molecule-1 (ICAM-1) expression and increase in leukocyte function-associated antigen-1 (LFA-1) positive cells in nephritic glomeruli significantly declined with butein treatment. In the further investigation to clarify the effects of butein on ICAM-1 expression, human umbilical vein endothelial cells were treated with butein in the presence of tumor necrosis factor-alpha (TNF-alpha) or phorbol 12-myristate 13-acetate (PMA). Butein prevented the up-regulation of ICAM-1 expression mediated by TNF-alpha or PMA on human umbilical vein endothelial cells in a dose-dependent manner. When human umbilical vein endothelial cells or neutrophils were treated with butein, the adhesion of neutrophils to human umbilical vein endothelial cells was suppressed. These data suggest that the antinephritic action of butein is due to inhibition of intraglomerular accumulation of leukocytes through the prevention of the up-regulation of ICAM-1 and the inhibition of a function of adhesion molecules on the surface of leukocytes.
Collapse
Affiliation(s)
- K Hayashi
- Department of Pharmacology, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | | | | | | |
Collapse
|
43
|
Balaban N, Moni J, Shannon M, Dang L, Murphy E, Goldkorn T. The effect of ionizing radiation on signal transduction: antibodies to EGF receptor sensitize A431 cells to radiation. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1314:147-56. [PMID: 8972728 DOI: 10.1016/s0167-4889(96)00068-7] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
What determines the degree of cell-resistance or sensitivity to ionizing radiation is not yet known. As a corollary to the ability of ceramide to induce apoptosis, some questions arise as to whether malignant cells escape apoptosis because of their inability to mount a ceramide response to inducers of apoptosis. To shed more light on the molecular mechanisms of tumor cell response to radiation, we tested whether exposure to ionizing radiation (of 200-1000 cGy) is associated with changes in ceramide levels in A431 tumor epithelial cells and whether the ability of ceramide to induce apoptosis is inhibited by protein kinase C (PKC) activation. Our studies demonstrate an immediate decrease in cellular levels of ceramide in response to radiation, while sphingosine levels increase. Under the same conditions the cellular 1,2-diacylglycerol (DAG) levels decrease as well, being accompanied by the translocation of PKC alpha from the membrane to the cytoplasm. Elevation of membrane PKC levels by 12-O-tetradecanoylphorbol 13-acetate (TPA) treatment had no effect on cell survival after irradiation, while treatment with EGF during and after irradiation augmented cell survival. Moreover, monoclonal antibodies to the EGF receptor (EGFR) sensitize cells to radiation by facilitating radiation-induced apoptosis. It is thus plausible that in human Squamous carcinoma cells, radiation activates predominantly the EGFR to induce resistance, while both sphingomyelin and PKC signal transduction pathways are deactivated and demonstrate no significant role in the modulation of the sensitivity or the resistance of A431 cells to ionizing radiation.
Collapse
Affiliation(s)
- N Balaban
- Department of Internal Medicine, University of California, Davis 95616, USA
| | | | | | | | | | | |
Collapse
|
44
|
Doerrler WT, Ye J, Falck JR, Lehrman MA. Acylation of glucosaminyl phosphatidylinositol revisited. Palmitoyl-CoA dependent palmitoylation of the inositol residue of a synthetic dioctanoyl glucosaminyl phosphatidylinositol by hamster membranes permits efficient mannosylation of the glucosamine residue. J Biol Chem 1996; 271:27031-8. [PMID: 8900192 DOI: 10.1074/jbc.271.43.27031] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Two critical steps in the assembly of yeast and mammalian glycosylphosphatidylinositol (GPI) anchor precursors are palmitoylation of the inositol residue and mannosylation of the glucosamine residue of the glucosaminyl phosphatidylinositol (GlcNalpha-PI) intermediate. Palmitoylation has been reported to be acyl-CoA dependent in yeast membranes (Costello, L. C., and Orlean, P. (1992) J. Biol. Chem. 267, 8599-8603) but strictly acyl-CoA independent in rodent membranes (Stevens, V. L., and Zhang, H. (1994) J. Biol. Chem. 269, 31397-31403), and thus poorly conserved. In addition, it was suggested that acylation must precede mannosylation in both yeast (Costello, L. C., and Orlean, P. (1992) J. Biol. Chem. 276, 8599-8603) and rodent (Urakaze, M., Kamitani, T., DeGasperi, R., Sugiyama, E., Chang, H.-M., Warren, C. D., and Yeh, E. T. H. (1992) J. Biol. Chem. 267, 6459-6462) cells because GlcNalpha-acyl-PI accumulates in vivo when mannosylation is blocked. However, GlcNalpha-acyl-PI accumulation would also be expected if mannosylation and acylation were independent of each other. These issues were addressed by the use of a synthetic dioctanoyl GlcNalpha-PI analogue (GlcNalpha-PI(C8)) as an in vitro substrate for GPI-synthesizing enzymes in Chinese hamster ovary cell membranes. GlcNalpha-PI(C8) was acylated in an manner requiring acyl-CoA. Thus, the process involving acyl-CoA reported for yeast has been conserved in mammals. Furthermore, both GlcNalpha-PI(C8) and GlcNalpha-acyl-PI(C8) could be mannosylated in vitro, but mannosylation of the latter was significantly more efficient. This provides direct support for the earlier suggestion that acylation precedes mannosylation in rodents cells. A similar result was also observed with the Saccharomyces cerevisiae mannosyltransferase. In contrast, it has been reported that mannosylation of endogenous GlcNalpha-PI by Trypansoma brucei membranes occurs without prior acylation. The same result was obtained with GlcNalpha-PI(C8), confirming that the mannosyltransferase of trypanosomes is divergent from those in yeasts and rodents.
Collapse
Affiliation(s)
- W T Doerrler
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, Texas 75235-9041, USA
| | | | | | | |
Collapse
|
45
|
Jayadev S, Hannun YA. Ceramide: role in growth inhibitory cascades. JOURNAL OF LIPID MEDIATORS AND CELL SIGNALLING 1996; 14:295-301. [PMID: 8906575 DOI: 10.1016/0929-7855(96)00538-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- S Jayadev
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | | |
Collapse
|
46
|
Blöchl A, Sirrenberg C. Neurotrophins stimulate the release of dopamine from rat mesencephalic neurons via Trk and p75Lntr receptors. J Biol Chem 1996; 271:21100-7. [PMID: 8702878 DOI: 10.1074/jbc.271.35.21100] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We analyzed the short term effect of neurotrophins on mesencephalic neuronal cultures of embryonic (E14) rats with respect to which receptors mediate the actions. Brain-derived neurotrophic factor (BDNF) or neurotrophin-3 enhanced within minutes in a dose-dependent manner (2, 20, 100 ng/ml for 5 min) depolarization-induced (KCl, 30 mM 5 min) and basal dopamine release, but nerve growth factor (NGF) was only effective at high doses (100 ng/ml). The effect of BDNF, but not of NGF, was blocked by K252a or K252b. BDNF, but not NGF, phosphorylated trkB receptors. The NGF-induced, but not the BDNF-induced effect upon the release of dopamine was blocked by anti-p75 antibody MC192. C2-ceramide, an analogue of ceramide, the second messenger of the sphingomyelin pathway, and sphingomyelinase itself induced a release of dopamine comparable with the effect of NGF. NGF, but not BDNF, increased ceramide production. In addition, simultaneous treatment with BDNF and NGF led to a partial prevention of the NGF-stimulated, p75(Lntr)-mediated effect. We conclude that BDNF stimulates the release of dopamine by activation of the trkB receptor, whereas NGF affects the release via the p75(Lntr) receptor inducing the sphingomyelin pathway.
Collapse
Affiliation(s)
- A Blöchl
- Max-Planck-Institute for Psychiatry, Department of Neurochemistry, D-82152 Martinsried, Federal Republic of Germany
| | | |
Collapse
|
47
|
Bielawska A, Greenberg MS, Perry D, Jayadev S, Shayman JA, McKay C, Hannun YA. (1S,2R)-D-erythro-2-(N-myristoylamino)-1-phenyl-1-propanol as an inhibitor of ceramidase. J Biol Chem 1996; 271:12646-54. [PMID: 8647877 DOI: 10.1074/jbc.271.21.12646] [Citation(s) in RCA: 164] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
In this study, we have examined the cellular and biochemical activities of the ceramide analog (1S,2R)-D-erythro-2-(N-myristoylamino)-1-phenyl-1-propanol (D-erythro-MAPP). Addition of 5 microM D-e-MAPP to HL-60 human promyelocytic leukemia cells resulted in a concentration- and time-dependent growth suppression accompanied by an arrest in the G0/G1 phase of the cell cycle; thus mimicking the action of exogenous ceramides. Its enantiomer L-e-MAPP was without effect. Two lines of evidence suggested that D-e-MAPP may not function as a direct analog of ceramide. First, D-e-MAPP possesses a stereochemical configuration opposite to that of D-erythro-ceramide. Second, D-e-MAPP failed to activate ceramide-activated protein phosphatase in vitro. Therefore, we examined if D-e-MAPP functioned indirectly by modulating endogenous ceramide levels. The addition of D-e-MAPP to cells, but not L-e-MAPP, caused a time- and concentration-dependent elevation in endogenous ceramide levels reaching greater than 3-fold over baseline following 24 h of treatment. Both D-e-MAPP and L-e-MAPP underwent similar uptake by HL-60 cells. D-e-MAPP was poorly metabolized, and remained intact in cells, whereas L-e-MAPP underwent a time- and concentration-dependent metabolism; primarily through N-deacylation. In vitro, L-e-MAPP was metabolized by alkaline ceremidase to an extent similar to that seen with C16-ceramide. D-e-MAPP was not metabolized. Instead, D-e-MAPP inhibited alkaline ceramidase activity in vitro with an IC50 of 1-5 microM. D-e-MAPP did not modulate the activity of other ceramide metabolizing enzymes in vitro or in cells, and it was a poor inhibitor of acid ceramidase (IC50>500 microM). Finally, D-e-MAPP inhibited the metabolism of L-e-MAPP in cells. These studies demonstrate that D-e-MAPP functions as an inhibitor of alkaline ceramidase in vitro and in cells resulting in elevation in endogenous levels of ceramide with the consequent biologic effects of growth suppression and cell cycle arrest. These studies point to an important role for ceramidases in the regulation of endogenous levels of ceramide.
Collapse
Affiliation(s)
- A Bielawska
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA
| | | | | | | | | | | | | |
Collapse
|
48
|
Jarvis WD, Fornari FA, Traylor RS, Martin HA, Kramer LB, Erukulla RK, Bittman R, Grant S. Induction of apoptosis and potentiation of ceramide-mediated cytotoxicity by sphingoid bases in human myeloid leukemia cells. J Biol Chem 1996; 271:8275-84. [PMID: 8626522 DOI: 10.1074/jbc.271.14.8275] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Prior studies demonstrated that ceramide promotes apoptotic cell death in the human myeloid leukemia cell lines HL-60 and U937 (Jarvis, W. D., Kolesnick, R. N., Fornari, F. A., Jr., Traylor, R. S., Gewirtz, D. A., and Grant, S. (1994) Proc. Natl. Acad. Sci. U. S. A. 91, 73-77), and that this lethal process is potently suppressed by diglyceride (Jarvis, W. D., Fornari, F. A., Jr., Browning, J. L., Gewirtz, D. A., Kolesnick, R. N., and Grant, S. (1994) J. Biol. Chem. 269, 31685-31692). The present findings document the intrinsic ability of sphingoid bases to induce apoptosis in HL-60 and U937 cells. Exposure to either sphingosine or sphinganine (0. 001 10 microM) for 6 h promoted apoptotic degradation of genomic DNA as indicated by (a) electrophoretic resolution of 50-kilobase pair DNA loop fragments and 0.2-1.2-kilobase pair DNA fragment ladders on agarose gels, and (b) spectrofluorophotometric determination of the formation and release of double-stranded fragments and corresponding loss of integrity of bulk DNA. DNA damage correlated directly with reduced cloning efficiency and was associated with the appearance of apoptotic cytoarchitectural traits. At sublethal concentrations (</=750 nM), however, sphingoid bases synergistically augmented the apoptotic capacity of ceramide (10 microM), producing both a leftward shift in the ceramide concentration-response profile and a pronounced increase in the response to maximally effective levels of ceramide. Thus, sphingosine and sphinganine increased both the potency and efficacy of ceramide. The apoptotic capacity of bacterial sphingomyelinase (50 milliunits/ml) was similarly enhanced by either (a) acute co-exposure to highly selective pharmacological inhibitors of protein kinase C such as calphostin C and chelerythrine or (b) chronic pre-exposure to the non-tumor-promoting protein kinase C activator bryostatin 1, which completely down-modulated total assayable protein kinase C activity. These findings demonstrate that inhibition of protein kinase C by physiological or pharmacological agents potentiates the lethal actions of ceramide in human leukemia cells, providing further support for the emerging concept of a cytoprotective function of the protein kinase C isoenzyme family in the regulation of leukemic cell survival.
Collapse
Affiliation(s)
- W D Jarvis
- Department of Medicine, Medical College of Virginia, Richmond, 23298-0230, USA
| | | | | | | | | | | | | | | |
Collapse
|
49
|
Perez M, Donato NJ. Activation of epidermal growth factor receptor tyrosine phosphorylation by tumor necrosis factor correlates with loss of cytotoxic activity. J Interferon Cytokine Res 1996; 16:307-14. [PMID: 9162524 DOI: 10.1089/jir.1996.16.307] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
TNF induces cytotoxicity in human tumor cells through a receptor-mediated process with unknown signaling characteristics. Evidence suggests that overexpression of transmembrane growth factor receptors with intrinsic tyrosine kinase activity may suppress the antiproliferative or cytotoxic activity of TNF, suggesting antagonism between these two signaling pathways in tumor cells. To investigate TNF cytotoxic signal transduction, ME-180 cervical carcinoma cell variants were isolated that expressed complete cytotoxic sensitivity (ME-180S) or resistance (ME-180R) to TNF but identical levels of p55 TNF receptor expression. ME-180R cells expressed threefold higher EGFR than the ME-180S cell line and TNF treatment stimulated EGFR tyrosine phosphorylation only in resistant cells. Activation of tyrosine phosphorylation in ME-180R cells was TNF concentration dependent and maximally stimulated (three- to-five-fold) after 10-15 minutes of treatment. Other tyrosine phosphoproteins were not affected by TNF incubation demonstrating specific TNF-stimulated tyrosine phosphomodulation of EGFR. Pretreatment with the tyrosine kinase inhibitor tryphostin before incubation with TNF resulted in partial reversal of TNF cytotoxic resistance in ME-180R cells and enhanced TNF responsiveness in ME-180S cells, suggesting a "protective" role for tyrosine phosphorylation in TNF-induced cytotoxicity. Together these results demonstrate that TNF-mediated tyrosine phosphorylation is differentially regulated in sensitive and resistant tumor cells and may play a critical role in the cytotoxic signaling process through differential expression or regulation of tyrosine protein kinases and phosphatases.
Collapse
Affiliation(s)
- M Perez
- Department of Bioimmunotherapy, Box 41, 1515 Holcombe Boulevard Houston, TX 77030, USA
| | | |
Collapse
|
50
|
Yatomi Y, Ruan F, Megidish T, Toyokuni T, Hakomori S, Igarashi Y. N,N-dimethylsphingosine inhibition of sphingosine kinase and sphingosine 1-phosphate activity in human platelets. Biochemistry 1996; 35:626-33. [PMID: 8555236 DOI: 10.1021/bi9515533] [Citation(s) in RCA: 136] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Potential sphingosine (Sph) metabolites include phosphorylated, N-acylated, and N-methylated derivatives. Phosphorylated Sph, i.e., sphingosine 1-phosphate (Sph-1-P), may act as an autocrine stimulator of blood platelets, as it is abundantly stored in platelets and released extracellularly and its exogenous addition induces platelet activation. In this study, we evaluated Sph-1-P formation and its effects in human platelets in the presence of other Sph metabolites. On addition of [3H]Sph to intact platelets, the label was rapidly converted to Sph-1-P. This conversion into [3H]Sph-1-P was inhibited by N,N-dimethylsphingosine (DMS) in a dose-dependent manner, but not by other structurally related Sph derivatives, including ceramide. The inhibition of Sph-1-P formation by DMS was reproduced using a cell-free system (Sph kinase obtained from platelet cytosolic fractions) and much stronger than that by DL-threo-dihydrosphingosine, which had been considered to be the strongest inhibitor of Sph kinase. Administration of DMS to intact platelets resulted in a decrease in Sph-1-P mass and an increase in Sph mass. Furthermore, DMS inhibited the release of Sph-1-P from platelets stimulated with 12-O-tetradecanoylphorbol 13-acetate and inhibited platelet aggregation induced by exogenous addition of Sph-1-P. Collectively, our results indicate that DMS is useful as a Sph kinase inhibitor and that Sph-1-P actions as an autocrine stimulator of platelets are inhibited by DMS.
Collapse
Affiliation(s)
- Y Yatomi
- Biomembrane Institute, Seattle, Washington 98119, USA
| | | | | | | | | | | |
Collapse
|