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Rodriguez-Cuenca S, Pellegrinelli V, Campbell M, Oresic M, Vidal-Puig A. Sphingolipids and glycerophospholipids - The "ying and yang" of lipotoxicity in metabolic diseases. Prog Lipid Res 2017; 66:14-29. [PMID: 28104532 DOI: 10.1016/j.plipres.2017.01.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 11/30/2016] [Accepted: 01/05/2017] [Indexed: 12/14/2022]
Abstract
Sphingolipids in general and ceramides in particular, contribute to pathophysiological mechanisms by modifying signalling and metabolic pathways. Here, we present the available evidence for a bidirectional homeostatic crosstalk between sphingolipids and glycerophospholipids, whose dysregulation contributes to lipotoxicity induced metabolic stress. The initial evidence for this crosstalk originates from simulated models designed to investigate the biophysical properties of sphingolipids in plasma membrane representations. In this review, we reinterpret some of the original findings and conceptualise them as a sort of "ying/yang" interaction model of opposed/complementary forces, which is consistent with the current knowledge of lipid homeostasis and pathophysiology. We also propose that the dysregulation of the balance between sphingolipids and glycerophospholipids results in a lipotoxic insult relevant in the pathophysiology of common metabolic diseases, typically characterised by their increased ceramide/sphingosine pools.
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Affiliation(s)
- S Rodriguez-Cuenca
- Metabolic Research Laboratories, Wellcome Trust MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge. Cambridge, UK.
| | - V Pellegrinelli
- Metabolic Research Laboratories, Wellcome Trust MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge. Cambridge, UK
| | - M Campbell
- Metabolic Research Laboratories, Wellcome Trust MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge. Cambridge, UK
| | - M Oresic
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, FI -20520 Turku, Finland
| | - A Vidal-Puig
- Metabolic Research Laboratories, Wellcome Trust MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge. Cambridge, UK; Wellcome Trust Sanger Institute, Hinxton, UK.
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2
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Azzouz S, Maache M, Sánchez-Moreno M, Petavy AF, Osuna A. Effect of alkyl-lysophospholipids on some aspects of the metabolism of Leishmania donovani. J Parasitol 2008; 93:1202-7. [PMID: 18163358 DOI: 10.1645/ge-1086r1.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Alkyl-lysophospholipids (ALPs), developed initially to be antitumor agents, have proved highly effective in the treatment of visceral leishmaniasis, a disease caused by the species making up the protozoan complex Leishmania donovani. Although their effectiveness is known, the mode of action against this parasite is not completely understood. In the present work, we have studied the effect of 3 derivatives, edelfosine, miltefosine, and ilmofosine. Using nuclear magnetic resonance spectroscopy ('H-NMR), we have examined the excreted catabolites from glucose metabolism in the promastigote forms treated with these compounds. The ALPs at concentrations of 19 and 38 microM inhibit the excretion of acetate, succinate, and pyruvate. The effect of edelfosine, miltefosine, and ilmofosine on the activity of the enzymes hexokinase, glycerolkinase 3-PD, phosphoglucose isomerase, superoxide dismutase, and phospholipase C were also examined. Glycerolkinase 3-PD and phosphoglucose isomerase are generally insensitive to the compounds, whereas hexokinase and superoxide dismutase are inhibited by miltefosine and ilmofosine. The ALPs exhibited an activated effect against the phospholipase C activity. Alkyl-lysophospholipids were shown to have a significant effect on several enzymes in important biochemical pathways indispensable for the survival of L. donovani promasigotes.
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Affiliation(s)
- S Azzouz
- Institute of Biotechnology, Department of Parasitology, Faculty of Sciences Campus Fuentenueva CP, Granada, Spain
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3
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Mollinedo F. Antitumour ether lipids: proapoptotic agents with multiple therapeutic indications. Expert Opin Ther Pat 2007. [DOI: 10.1517/13543776.17.4.385] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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4
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Urbina JA. Mechanisms of action of lysophospholipid analogues against trypanosomatid parasites. Trans R Soc Trop Med Hyg 2006; 100 Suppl 1:S9-S16. [PMID: 16930650 DOI: 10.1016/j.trstmh.2006.03.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 02/18/2006] [Accepted: 03/09/2006] [Indexed: 10/24/2022] Open
Abstract
Lysophospholipid analogues (LPAs) comprise a class of metabolically stable compounds that have been developed as anticancer agents for over two decades, but which have also potent and selective antiparasitic activity, particularly against trypanosomatid parasites such as Leishmania and Trypanosoma cruzi, both in vitro and in vivo. The in vivo activities of LPAs result from direct effects on their target cells and are not dependent on a functional immune system. Because of their chemical nature, LPAs have a potential for interaction with a variety of subcellular structures and biochemical pathways. However, in mammalian cells LPA-induced growth inhibition and programmed cell death is usually associated with a blockade of phosphatidylcholine (PC) biosynthesis at the level of CTP: phosphocholine citidyltransferase, probably through an increase of cellular ceramide levels due to depressed sphingomyelin synthesis. Although in trypanosomatid parasites much less information is available, inhibition of PC biosynthesis by LPA has also been documented but at the level of phosphatidylethanolamine N-methyl-transferase, as well as LPA-induced classical apoptotic phenomena. The higher activity of LPAs as inhibitors of PC biosynthesis in parasites than in mammalian cells, probably due to different biochemical pathways involved in the two types of cells, could explain their selective antiparasitic action in vivo.
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Affiliation(s)
- Julio A Urbina
- Laboratorio de Química Biológica, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Cientificas, Apartado 21827, Caracas 1020A, Venezuela.
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5
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Abstract
The well-known problems of classic treatment of the leishmaniases with pentavalent antimony (reduced efficacy), difficulties of administration and increasing frequency and severity of adverse events have stimulated the search for new drugs to treat these diseases. Other injectable, oral and topical drugs have not been consistently effective, especially in the modern World. Beginning in 1998, Indian researchers conducted several trials with hexadecylphosphocholine (miltefosine) in patients with visceral leishmaniasis, and in 1999, clinical studies were initiated in Colombia for cutaneous disease. More than 2500 patients have been treated, including patients with diffuse cutaneous leishmaniasis, mucosal disease and patients coinfected with HIV. Cure rates between 91 and 100% were reached with a dose of 2.5 mg/kg/day for 28 days, with no difference between treatment-naive and relapsing patients. Mild gastrointestinal events were present in 35-60% of patients and 10-20% had mild transaminase and creatinine elevations. Miltefosine has potent leishmanicidal activity as a consequence of its interference in parasite metabolic pathways and the induction of apoptosis. Miltefosine is the first effective and safe oral agent with the potential to treat all major clinical presentations of leishmaniasis.
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Affiliation(s)
- Jaime Soto
- CIBIC, Centro de Investigaciones Bioclínicas de la Fundación FADER, Bogotá, Colombia.
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6
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Lochnit G, Bongaarts R, Geyer R. Searching new targets for anthelminthic strategies: Interference with glycosphingolipid biosynthesis and phosphorylcholine metabolism affects development of Caenorhabditis elegans. Int J Parasitol 2005; 35:911-23. [PMID: 15885697 DOI: 10.1016/j.ijpara.2005.02.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Revised: 02/07/2005] [Accepted: 02/22/2005] [Indexed: 11/17/2022]
Abstract
Nematode infections are amongst the most abundant diseases of man and animals. They are characterised by a low mortality but high morbidity, thus reflecting the adaptation of these parasites to their hosts. Resistance as well as severe side-effects and efficacies restricted to distinct larval stages or parasites of the anthelmithics used at present require the urgent development of new and more nematode-specific drugs, targeting enzymes of parasite restricted biosynthetic routes. Caenorhabditis elegans has been found to be a good model system for parasitic nematodes, drug screening and developmental studies. Structural analyses have revealed nematode-specific glycosphingolipid structures of the arthro-series, carrying in part, phosphorylcholine substituents. These biomolecules appear to play important roles in nematode development, fertility and survival within the host and are, therefore, good target-candidates for the development of new anthelminthic strategies. Here we show that RNAi experiments targeting enzymes of glycosphingolipid biosynthesis or choline metabolism result, in part, in a drastic reduction of fertility. We further tested various chemical inhibitors of these pathways and found significant effects on the development of the worms, resulting in developmental arrest, sterility and, in part, lethality. Such inhibitors can, therefore, help to define new classes of anthelminthics.
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Affiliation(s)
- Günter Lochnit
- Faculty of Medicine, Institute of Biochemistry, University of Giessen, Friedrichstrasse 24, D-35392 Giessen, Germany.
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7
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Hojjati MR, Li Z, Zhou H, Tang S, Huan C, Ooi E, Lu S, Jiang XC. Effect of myriocin on plasma sphingolipid metabolism and atherosclerosis in apoE-deficient mice. J Biol Chem 2004; 280:10284-9. [PMID: 15590644 DOI: 10.1074/jbc.m412348200] [Citation(s) in RCA: 237] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sphingolipids play a very important role in cell membrane formation, signal transduction, and plasma lipoprotein metabolism, all of which may well have an impact on the development of atherosclerosis. To investigate the relationship between sphingolipid metabolism and atherosclerosis, we utilized myriocin to inhibit mouse serine palmitoyl-CoA transferase (SPT), the key enzyme for sphingolipid biosynthesis. We injected 8-week-old apoE-deficient mice with myriocin (0.3 mg/kg/every other day, intraperitoneal) for 60 days. On a chow diet, myriocin treatment caused a significant decrease (50%) in liver SPT activity (p < 0.001), significant decreases in plasma sphingomyelin, ceramide, and sphingosine-1-phosphate levels (54, 32, and 73%, respectively) (p < 0.0001), and a significant increase in plasma phosphatidylcholine levels (91%) (p < 0.0001). Plasma total cholesterol and triglyceride levels demonstrated no significant changes, but there was a significant decrease in atherosclerotic lesion area (42% in root and 36% in en face assays) (p < 0.01). On a high fat diet, myriocin treatment caused marked decreases in plasma sphingomyelin, ceramide, and sphingosine-1-phosphate levels (59, 66, and 81%, respectively) (p < 0.0001), and a marked increase in plasma phosphatidylcholine levels (100%) (p < 0.0001). Total cholesterol and triglyceride demonstrated no significant changes, but there was a significant decrease in atherosclerotic lesion area (39% in root and 37% in en face assays) (p < 0.01). These results indicate that, apart from cholesterol levels, sphingolipids have an effect on atherosclerotic development and that SPT has proatherogenic properties. Thus, inhibition of SPT activity could be an alternative treatment for atherosclerosis.
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Affiliation(s)
- Mohammad Reza Hojjati
- Department of Anatomy and Cell Biology, State University of New York Downstate Medical Center, 450 Clarkson Ave., Brooklyn, New York 11203, USA
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8
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von Haefen C, Gillissen B, Hemmati PG, Wendt J, Güner D, Mrozek A, Belka C, Dörken B, Daniel PT. Multidomain Bcl-2 homolog Bax but not Bak mediates synergistic induction of apoptosis by TRAIL and 5-FU through the mitochondrial apoptosis pathway. Oncogene 2004; 23:8320-32. [PMID: 15467752 DOI: 10.1038/sj.onc.1207971] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The death ligand TRAIL synergizes with DNA-damaging therapies such as chemotherapeutic drugs or ionizing irradiation. Here, we show that the synergism of TRAIL and 5-fluorouracil (5-FU) and cross-sensitization between TRAIL and 5-FU for induction of apoptosis, entirely depend on Bax proficiency in human DU145 and HCT116 carcinoma cells. DU145 prostate carcinoma cells that have lost Bax protein expression due to mutation fail to release cytochrome c and to activate caspase-3 and -9 when exposed to TRAIL and 5-FU. In contrast, TRAIL sensitized for 5-FU-induced apoptosis and vice versa upon reconstitution of Bax expression. Isobolographic analyses of ED50 doses for 5-FU at increasing TRAIL concentrations showed a clear synergism of TRAIL and 5-FU in Bax-expressing cells. In contrast, the effect was merely additive in DU145 cells lacking Bax. Notably, both DU145 and HCT116 Bax-deficient cells still express Bak. This indicates that Bak is not sufficient to mediate cross-sensitization and synergism between 5-FU and TRAIL. Stable overexpression of Bak in DU145 sensitized for epirubicin-induced apoptosis but failed to confer synergy between TRAIL and 5-FU. Moreover, we show by the use of EGFP-tagged Bax and Bak that TRAIL and 5-FU synergistically trigger oligomerization and clustering of Bax but not Bak. These data clearly establish distinct roles for Bax and Bak in linking the TRAIL death receptor pathway to the mitochondrial apoptosis signaling cascade and delineate a higher degree of specificity in signaling for cell death by multidomain Bcl-2 homologs.
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Affiliation(s)
- Clarissa von Haefen
- Department of Hematology, Oncology and Tumor Immunology, University Medical Center Charité, Humboldt University, Berlin
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9
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Lang KS, Myssina S, Brand V, Sandu C, Lang PA, Berchtold S, Huber SM, Lang F, Wieder T. Involvement of ceramide in hyperosmotic shock-induced death of erythrocytes. Cell Death Differ 2004; 11:231-43. [PMID: 14615798 DOI: 10.1038/sj.cdd.4401311] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Erythrocytes lack nuclei and mitochondria, the organelles important for apoptosis of nucleated cells. However, following increase of cytosolic Ca(2+) activity, erythrocytes undergo cell shrinkage, cell membrane blebbing and breakdown of phosphatidylserine asymmetry, all features typical for apoptosis in nucleated cells. The same events are observed following osmotic shock, an effect mediated in part by activation of Ca(2+)-permeable cation channels. However, erythrocyte death following osmotic shock is blunted but not prevented in the absence of extracellular Ca(2+) pointing to additional mechanisms. As shown in this study, osmotic shock (950 mOsm) triggers sphingomyelin breakdown and formation of ceramide. The stimulation of annexin binding following osmotic shock is mimicked by addition of ceramide or purified sphingomyelinase and significantly blunted by genetic (aSM-deficient mice) or pharmacologic (50 microM 3,4-dichloroisocoumarin) knockout of sphingomyelinase. The effect of ceramide is blunted but not abolished in the absence of Ca(2+). Conversely, osmotic shock-induced annexin binding is potentiated in the presence of sublethal concentrations of ceramide. In conclusion, ceramide and Ca(2+) entry through cation channels concert to trigger erythrocyte death during osmotic shock.
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Affiliation(s)
- K S Lang
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tübingen, Germany
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10
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Myssina S, Huber SM, Birka C, Lang PA, Lang KS, Friedrich B, Risler T, Wieder T, Lang F. Inhibition of erythrocyte cation channels by erythropoietin. J Am Soc Nephrol 2004; 14:2750-7. [PMID: 14569084 DOI: 10.1097/01.asn.0000093253.42641.c1] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Recombinant human erythropoietin therapy is used to counteract anemia that is the result of renal insufficiency. It stimulates the formation of peripheral blood erythrocytes by inhibiting apoptosis of erythrocyte precursor cells. Mature erythrocytes have similarly been shown to undergo apoptosis. Hyperosmotic shock and Cl(-) removal activate a Ca(2+)-permeable, ethylisopropylamiloride-inhibitable cation channel. The subsequent increase of cytosolic Ca(2+) activates a scramblase that breaks down cell membrane phosphatidylserine asymmetry, leading to annexin binding. Studied was whether channel activity and erythrocyte cell death are regulated by erythropoietin. Scatchard plot analysis disclosed low-abundance, high-affinity binding of (125)I-erythropoietin to erythrocytes. Whole cell patch clamp experiments revealed significant inhibition of the ethylisopropylamiloride-sensitive current by 1 U/ml erythropoietin. Cl(-) removal triggered annexin binding, an effect abrogated by erythropoietin (1 U/ml) but not by GM-CSF (10 ng/ml). Osmotic shock (700 mOsm) stimulated annexin binding within 24 h in the majority of the erythrocytes, an effect blunted by erythropoietin (1 U/ml) but not by GM-CSF (10 ng/ml). In the nominal absence of Ca(2+), the effect of osmotic shock was blunted and the effect of erythropoietin abolished. In hemodialysis patients, intravenous administration of erythropoietin (50 IU/kg) within 4 h decreased the number of annexin binding circulating erythrocytes. Erythropoietin binds to erythrocytes and inhibits volume-sensitive erythrocyte cation channels and thus the breakdown of phosphatidylserine asymmetry after activation of this channel. The effect could prolong the erythrocyte lifespan and may contribute to the enhancement of the erythrocyte number during erythropoietin therapy in dialysis patients.
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11
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Lang KS, Duranton C, Poehlmann H, Myssina S, Bauer C, Lang F, Wieder T, Huber SM. Cation channels trigger apoptotic death of erythrocytes. Cell Death Differ 2003; 10:249-56. [PMID: 12700653 DOI: 10.1038/sj.cdd.4401144] [Citation(s) in RCA: 253] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Erythrocytes are devoid of mitochondria and nuclei and were considered unable to undergo apoptosis. As shown recently, however, the Ca(2+)-ionophore ionomycin triggers breakdown of phosphatidylserine asymmetry (leading to annexin binding), membrane blebbing and shrinkage of erythrocytes, features typical for apoptosis in nucleated cells. In the present study, the effects of osmotic shrinkage and oxidative stress, well-known triggers of apoptosis in nucleated cells, were studied. Exposure to 850 mOsm for 24 h, to tert-butyl-hydroperoxide (1 mM) for 15 min, or to glucose-free medium for 48 h, all elicit erythrocyte shrinkage and annexin binding, both sequelae being blunted by removal of extracellular Ca(2+) and mimicked by ionomycin (1 microM). Osmotic shrinkage and oxidative stress activate Ca(2+)-permeable cation channels and increase cytosolic Ca(2+) concentration. The channels are inhibited by amiloride (1 mM), which further blunts annexin binding following osmotic shock, oxidative stress and glucose depletion. In conclusion, osmotic and oxidative stress open Ca(2+)-permeable cation channels in erythrocytes, thus increasing cytosolic Ca(2+) activity and triggering erythrocyte apoptosis.
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Affiliation(s)
- K S Lang
- Department of Physiology, University of Tübingen, Tübingen, Germany
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12
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Abstract
Phosphatidylcholine (PC) constitutes a major portion of cellular phospholipids and displays unique molecular species in different cell types and tissues. Inhibition of the CDP-choline pathway in most mammalian cells or overexpression of the hepatic phosphatidylethanolamine methylation pathway in hepatocytes leads to perturbation of PC homeostasis, growth arrest or even cell death. Although many agents that perturb PC homeostasis and induce cell death have been identified, the signaling pathways that mediate this cell death have not been well defined. This review summarizes recent progress in understanding the relationship between PC homeostasis and cell death.
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Affiliation(s)
- Zheng Cui
- Department of Pathology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1016, USA.
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13
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Ramos B, El Mouedden M, Claro E, Jackowski S. Inhibition of CTP:phosphocholine cytidylyltransferase by C(2)-ceramide and its relationship to apoptosis. Mol Pharmacol 2002; 62:1068-75. [PMID: 12391269 DOI: 10.1124/mol.62.5.1068] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Apoptosis induced by antitumor phospholipid analogs takes place after the inhibition of the CTP:phosphocholine cytidylyltransferase (CCT; EC 2.7.7.15) catalyzed step of phosphatidylcholine (PtdCho) biosynthesis. Exposure of cells to synthetic short-chain ceramide analogs also triggers apoptosis concomitant with decreased PtdCho biosynthesis, and the present study was undertaken to ascertain whether C(2)-ceramide inhibition of PtdCho synthesis is direct or secondary to other ceramide-mediated cellular responses. The exposure of COS-7 cells to either C(2)-ceramide, ET-18-OCH(3), or farnesol resulted in time- and dose-dependent apoptotic cell death. Cells treated with C(2)-ceramide or ET-18-OCH(3) selectively and immediately accumulated phosphocholine, whereas CDP-choline increased with farnesol treatment. In vitro assays of CCT activity demonstrated that C(2)-ceramide directly inhibited CCT. Comparison of different N-linked sphingosine derivatives suggests an inverse relationship between the length of the N-linked carbon chain and the derivatives ability to trigger apoptosis and inhibit CCT. Taken together, our results suggest CCT as a primary target for C(2)-ceramide inhibition that accounts for its cytotoxic effects.
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Affiliation(s)
- Belén Ramos
- Departamento de Fisiología, Universidad de Extremadura, Cáceres, Spain
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14
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Vaandrager AB, Houweling M. Effect of ceramides on phospholipid biosynthesis and its implication for apoptosis. Subcell Biochem 2002; 36:207-27. [PMID: 12037983 DOI: 10.1007/0-306-47931-1_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Affiliation(s)
- Arie B Vaandrager
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, University of Utrecht, P.O. Box 80176, 3508 TD Utrecht, The Netherlands
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Hoffmann K, Grafe F, Wohlrab W, Neubert RH, Brandsch M. Functional characterization of a high-affinity choline transport system in human keratinocytes. J Invest Dermatol 2002; 119:118-21. [PMID: 12164933 DOI: 10.1046/j.1523-1747.2002.01801.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study was performed to characterize the mechanism of choline transport into human keratinocytes. Uptake of [3H]choline was measured both in the HaCaT cell line and in native keratinocytes. Uptake in HaCaT cells was linear with time at least up to 10 min. There was little dependence of choline transport on sodium. Choline uptake was slightly stimulated by extracellular H+ with the pH optimum being 7.5. The uptake rate was saturable and indicated participation of a single transport system (Kt = 14.8 +/- 1.0 micro M, Vmax = 1.0 +/- 0.01 nmol per 10 min per mg protein). The choline uptake into HaCaT cells was inhibited by unlabeled choline, hemicholinium-3, and acetylcholine. The prototypical organic cation tetraethylammonium showed very little affinity for the choline uptake system in these cells. Several cationic drugs such as diphenhydramine, clonidine, and atropine also interacted with the transport system. Choline uptake in normal keratinocytes was very similar to that in HaCaT cells with respect to substrate specificity and affinity. We conclude that keratinocytes express a Na+ independent, high-affinity choline transport system. This system accepts many pharmacologically important organic cations as substrates. It is similar or identical to the choline carrier described in intestinal epithelial cells and in endothelial cells of the blood-brain barrier. The choline carrier seems to have relevance not only for the uptake of cationic drugs into the keratinocytes but also for the biosynthesis of skin lipids.
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Affiliation(s)
- Kathrin Hoffmann
- Department of Pharmacy, Institute of Pharmaceutics and Biopharmaceutics, Biozentrum of the University, Martin-Luther-University Halle-Wittenberg, D-06120 Halle/Saale, Germany
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16
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Wieder T, Essmann F, Prokop A, Schmelz K, Schulze-Osthoff K, Beyaert R, Dörken B, Daniel PT. Activation of caspase-8 in drug-induced apoptosis of B-lymphoid cells is independent of CD95/Fas receptor-ligand interaction and occurs downstream of caspase-3. Blood 2001; 97:1378-87. [PMID: 11222383 DOI: 10.1182/blood.v97.5.1378] [Citation(s) in RCA: 202] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The activation of caspase-8, a crucial upstream mediator of death receptor signaling, was investigated in epirubicin- and Taxol-induced apoptosis of B-lymphoma cells. This study was performed because the CD95/Fas receptor-ligand interaction, recruitment of the Fas-associated death domain (FADD) adaptor protein, and subsequent activation of procaspase-8 have been implicated in the execution of drug-induced apoptosis in other cell types. Indeed, active caspase-8 was readily detected after treatment of mature and immature B-lymphoid cells with epirubicin or Taxol. However, neither constitutive nor drug-induced expression of the CD95/Fas ligand was detectable in B-lymphoma cells. Furthermore, overexpression of a dominant-negative FADD mutant (FADDdn) did not block caspase-8 processing and subsequent DNA fragmentation, indicating that drug-induced caspase-8 activation was mediated by a CD95/Fas-independent mechanism. Instead, caspase-8 cleavage was slightly preceded by activation of caspase-3, suggesting that drug-induced caspase-8 activation in B-lymphoma cells is a downstream event mediated by other caspases. This assumption was confirmed in 2 experimental systems-zDEVD-fmk, a cell-permeable inhibitor of caspase-3-like activity, blocked drug-induced caspase-8 cleavage, and depletion of caspase-3 from cell extracts impaired caspase-8 cleavage after in vitro activation with dATP and cytochrome c. Thus, these data indicate that drug-induced caspase-8 activation in B-lymphoma cells is independent of death receptor signaling and is mediated by postmitochondrial caspase-3 activation.
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Affiliation(s)
- T Wieder
- Department of Hematology, Oncology and Tumor Immunology, University Medical Center Charité, Humboldt University of Berlin, Germany
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17
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Allan D. Lipid metabolic changes caused by short-chain ceramides and the connection with apoptosis. Biochem J 2000; 345 Pt 3:603-10. [PMID: 10642519 PMCID: PMC1220795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
The effects of the short-chain ceramides D-erythro-N-acetylsphingosine (C(2)-ceramide), 6-[N-(7-nitrobenz-2-oxa-1, 3-diazole-4-yl)amino]hexanoyl-D-erythro-sphingosine(NBD-ceramide) and N-[4,4-difluoro-5,7-dimethyl-4-bora-3a, 4a-diaza-s-indacene-3-pentanoyl]-D-erythro-sphingosine (DMB-ceramide) on the incorporation of [(14)C]acetate into baby-hamster kidney (BHK) fibroblasts have been examined. C(2)-ceramide at concentrations up to 20 microM caused an inhibition of synthesis of phosphatidylcholine (PtdCho), sphingolipids and cholesterol within 2 h. Similar effects in BHK cells were seen using other radioactive tracers ([(3)H]water, [(3)H]palmitate and [(3)H]choline) and using HL60 cells labelled with [(14)C]acetate. The inhibition of PtdCho synthesis corresponded to an accumulation of label in diacylglycerol and triacylglycerol, probably as a consequence of cytidylyltransferase blockade. With [(3)H]choline label, the decrease in sphingomyelin synthesis could be partly accounted for by accumulation of a slow-moving lipid, likely to be C(2)-sphingomyelin. NBD-ceramide also reduced sphingomyelin and cholesterol biosynthesis, but had much less effect on PtdCho and acylglycerols. In contrast, the only apparent effect of DMB-ceramide was to inhibit synthesis of sphingomyelin, with a reciprocal increase in DMB-sphingomyelin synthesis. However, all of these short-chain ceramides caused massive apoptosis after 18 h, whereas addition of N-acetyldihydrosphingosine or elevation of natural ceramide by treatment of cells with sphingomyelinase had little effect on lipid synthesis or apoptosis. The present findings suggest that the apoptotic effect of short-chain ceramides is sometimes associated with inhibition of cytidylyltransferase, but is more closely correlated with a competitive inhibition of normal sphingomyelin biosynthesis.
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Affiliation(s)
- D Allan
- Department of Physiology, University College London, University Street, London WC1E 6JJ, U.K.
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Bladergroen BA, Bussière M, Klein W, Geelen MJ, Van Golde LM, Houweling M. Inhibition of phosphatidylcholine and phosphatidylethanolamine biosynthesis in rat-2 fibroblasts by cell-permeable ceramides. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 264:152-60. [PMID: 10447683 DOI: 10.1046/j.1432-1327.1999.00589.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Phospholipids and sphingolipids are important precursors of lipid-derived second messengers such as diacylglycerol and ceramide, which participate in several signal transduction pathways and in that way mediate the effects of various agonists. The cross-talk between glycerophospholipid and sphingolipid metabolism was investigated by examining the effects of cell-permeable ceramides on phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) synthesis in Rat-2 fibroblasts. Addition of short-chain C6-ceramide to the cells resulted in a dose- and time-dependent inhibition of the CDP-pathways for PtdCho and PtdEtn synthesis. Treatment of cells for 4 h with 50 microM C6-ceramide caused an 83% and a 56% decrease in incorporation of radiolabelled choline and ethanolamine into PtdCho and PtdEtn, respectively. Exposure of the cells for longer time-periods (>/= 16 h) to 50 microM C6-ceramide resulted in apoptosis. The structural analogue dihydro-C6-ceramide did not affect PtdCho and PtdEtn synthesis. In pulse-chase experiments, radioactive choline and ethanolamine accumulated in CDP-choline and CDP-ethanolamine under the influence of C6-ceramide, suggesting that synthesis of both PtdCho and PtdEtn were inhibited at the final step in the CDP-pathways. Indeed, cholinephosphotransferase and ethanolaminephosphotransferase activities in membrane fractions from C6-ceramide-treated cells were reduced by 64% and 43%, respectively, when compared with control cells. No changes in diacylglycerol mass levels or synthesis of diacylglycerol from radiolabelled palmitate were observed. It was concluded that C6-ceramide affected glycerophospholipid synthesis predominantly by inhibition of the step in the CDP-pathways catalysed by cholinephosphotransferase and ethanolaminephosphotransferase.
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Affiliation(s)
- B A Bladergroen
- Department of Biochemistry and Cell Biology, Graduate School of Animal Health, Utrecht University, The Netherlands
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Wieder T, Reutter W, Orfanos CE, Geilen CC. Mechanisms of action of phospholipid analogs as anticancer compounds. Prog Lipid Res 1999; 38:249-59. [PMID: 10664795 DOI: 10.1016/s0163-7827(99)00004-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- T Wieder
- Department of Dermatology, University Medical Center Benjamin Franklin, Free University of Berlin, Berlin-Steglitz, Germany
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Wieder T, Orfanos CE, Geilen CC. Induction of ceramide-mediated apoptosis by the anticancer phospholipid analog, hexadecylphosphocholine. J Biol Chem 1998; 273:11025-31. [PMID: 9556584 DOI: 10.1074/jbc.273.18.11025] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The prototype of a new class of antiproliferative phospholipid analogs, hexadecylphosphocholine (HePC), has been shown to inhibit tumor growth and is currently used for the treatment of cutaneous metastases of mammary carcinomas. Although several cellular targets of HePC, e.g. protein kinase C and CTP:phosphocholine cytidylyltransferase, have been proposed, the mechanisms of HePC-induced anticancer activity are still unclear. Considering that the antiproliferative effect of HePC correlates with inhibition of phosphatidylcholine biosynthesis, which is tightly coupled to sphingomyelin biosynthesis, we tested the hypothesis that treatment of cells with the anticancer drug leads to increased cellular ceramide and subsequently to apoptotic cell death. In the present study, we showed that 25 micromol/liter HePC induced apoptosis. In further experiments, we demonstrated that HePC inhibited the incorporation of radiolabeled choline into phosphatidylcholine and at a later time point into sphingomyelin. This was confirmed by metabolic labeling of the lipid backbone using radiolabeled serine, and it was shown that HePC decreased the incorporation of serine into sphingomyelin by 35% and simultaneously increased the incorporation of serine into ceramide by 70%. Determination of the amount of ceramide revealed an increase of 53% in HePC-treated cells compared with controls. In accordance with the hypothesis that elevated ceramide levels may be the missing link between the metabolic effects of HePC and its proapoptotic properties, HePC-induced apoptosis was blocked by fumonisin B1, an inhibitor of ceramide synthesis. Furthermore, we found that membrane-permeable ceramides additively increased the apoptotic effect of HePC.
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Affiliation(s)
- T Wieder
- Department of Dermatology, University Medical Center Benjamin Franklin, The Free University of Berlin, 12200 Berlin, Germany
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Wieder T, Geilen CC, Kolter T, Sadeghlar F, Sandhoff K, Brossmer R, Ihrig P, Perry D, Orfanos CE, Hannun YA. Bcl-2 antagonizes apoptotic cell death induced by two new ceramide analogues. FEBS Lett 1997; 411:260-4. [PMID: 9271217 DOI: 10.1016/s0014-5793(97)00717-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ceramides which arise in part from the breakdown of sphingomyelin comprise a class of antiproliferative lipids and have been implicated in the regulation of programmed cell death better known as apoptosis. In the present study, two new synthetic ceramide analogues, N-thioacetylsphingosine and FS-5, were used in Molt 4 cells to induce cell death. Besides their cytotoxic effects at concentrations > or = 14 microM the data obtained clearly show that both analogues induced apoptosis at concentrations below this critical concentration as assessed by trypan blue exclusion and cleavage of the death substrate poly-(ADP-ribose) polymerase (PARP). Additional experiments in bcl-2-transfected Molt 4 cells revealed that the apoptotic but not the lytic effects of the analogues were antagonized by the apoptosis inhibitor Bcl-2. Furthermore, neither N-thio-acetylsphingosine nor FS-5 induced PARP cleavage in bcl-2-transfected Molt 4 cells indicating that the induction of apoptotic cell death by cell permeable ceramides is not due to unspecific disturbance of the cell membrane.
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Affiliation(s)
- T Wieder
- Department of Dermatology, University Medical Center Benjamin Franklin, The Free University of Berlin, Germany
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