151
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Romanowicz L, Bańkowski E. Preeclampsia-associated alterations in sphingolipid composition of the umbilical cord artery. Clin Biochem 2009; 42:1719-24. [DOI: 10.1016/j.clinbiochem.2009.07.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 07/03/2009] [Accepted: 07/06/2009] [Indexed: 10/20/2022]
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152
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Robertson RP. Beta-cell deterioration during diabetes: what's in the gun? Trends Endocrinol Metab 2009; 20:388-93. [PMID: 19748794 PMCID: PMC2756315 DOI: 10.1016/j.tem.2009.05.004] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Revised: 05/06/2009] [Accepted: 05/07/2009] [Indexed: 01/09/2023]
Abstract
Clinical management of patients with type 2 diabetes (T2D) successfully prevents extreme hyperglycemia but does not precisely control glucose levels throughout the day. The pathogenesis of T2D is akin to a double-barrel shotgun. The first trigger causes an explosion that sets genetic expression of the disease in motion; the second trigger discharges a host of environmental factors that worsen its clinical course. Candidate shells include glucolipotoxicity, cytokines, oxidative and endoplasmic reticulum stress and insulin resistance. This review considers how each candidate adversely impacts beta-cell function to create the downward spiral of glycemic control. Their roles in pathogenesis raise possibilities for new drug therapies designed to protect against adverse effects of residual hyperglycemia in patients treated with conventional drugs.
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Affiliation(s)
- R Paul Robertson
- Pacific Northwest Diabetes Research Institute, Seattle, WA 98122, USA.
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153
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Poitout V, Amyot J, Semache M, Zarrouki B, Hagman D, Fontés G. Glucolipotoxicity of the pancreatic beta cell. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1801:289-98. [PMID: 19715772 DOI: 10.1016/j.bbalip.2009.08.006] [Citation(s) in RCA: 269] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 08/13/2009] [Accepted: 08/13/2009] [Indexed: 02/07/2023]
Abstract
The concept of glucolipotoxicity refers to the combined, deleterious effects of elevated glucose and fatty acid levels on pancreatic beta-cell function and survival. Significant progress has been made in recent years towards a better understanding of the cellular and molecular basis of glucolipotoxicity in the beta cell. The permissive effect of elevated glucose on the detrimental actions of fatty acids stems from the influence of glucose on intracellular fatty acid metabolism, promoting the synthesis of cellular lipids. The combination of excessive levels of fatty acids and glucose therefore leads to decreased insulin secretion, impaired insulin gene expression, and beta-cell death by apoptosis, all of which probably have distinct underlying mechanisms. Recent studies from our laboratory have identified several pathways implicated in fatty acid inhibition of insulin gene expression, including the extracellular-regulated kinase (ERK1/2) pathway, the metabolic sensor Per-Arnt-Sim kinase (PASK), and the ATF6 branch of the unfolded protein response. We have also confirmed in vivo in rats that the decrease in insulin gene expression is an early defect which precedes any detectable abnormality in insulin secretion. While the role of glucolipotoxicity in humans is still debated, the inhibitory effects of chronically elevated fatty acid levels has been clearly demonstrated in several studies, at least in individuals genetically predisposed to developing type 2 diabetes. It is therefore likely that glucolipotoxicity contributes to beta-cell failure in type 2 diabetes as well as to the decline in beta-cell function observed after the onset of the disease.
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Affiliation(s)
- Vincent Poitout
- Montreal Diabetes Research Center, CRCHUM, Department of Medicine, University of Montreal, Montreal, QC, Canada.
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154
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Beauchamp E, Tekpli X, Marteil G, Lagadic-Gossmann D, Legrand P, Rioux V. N-Myristoylation targets dihydroceramide Delta4-desaturase 1 to mitochondria: partial involvement in the apoptotic effect of myristic acid. Biochimie 2009; 91:1411-9. [PMID: 19647031 DOI: 10.1016/j.biochi.2009.07.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Accepted: 07/16/2009] [Indexed: 12/20/2022]
Abstract
This study was designed to analyze the effect of myristic acid on ceramide synthesis and its related lipoapoptosis pathway. It was previously observed that myristic acid binds dihydroceramide Delta4-desaturase 1 (DES1) through N-myristoylation and activates this enzyme involved in the final de novo ceramide biosynthesis step. In the present study, we show first by immunofluorescence microscopy and subcellular fractionation that DES1 myristoylation targets part of the recombinant protein to the mitochondria in COS-7 cells. In addition, native dihydroceramide Delta4-desaturase activity was found in both the endoplasmic reticulum and mitochondria in rat hepatocytes. Dihydroceramide conversion to ceramide was increased in COS-7 cells expressing DES1 and incubated with myristic acid. The expression of the wild-type myristoylable DES1-Gly alone, but not the expression of the unmyristoylable mutant DES1-Ala, induced apoptosis of COS-7 cells. Finally, myristic acid alone also increased the production of cellular ceramide and had an apoptotic effect. This effect was potentiated on caspase activity when the myristoylable form of DES1 was expressed. Therefore, these results suggest that the myristoylation of DES1 can target the enzyme to the mitochondria leading to an increase in ceramide levels which in turn contributes to partially explain the apoptosis effect of myristic acid in COS-7 cells.
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Affiliation(s)
- Erwan Beauchamp
- Laboratoire de Biochimie-Nutrition Humaine, Agrocampus Ouest-INRA USC 2012, Rennes, France
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155
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Solivera J, Cerdán S, Pascual JM, Barrios L, Roda JM. Assessment of 31P-NMR analysis of phospholipid profiles for potential differential diagnosis of human cerebral tumors. NMR IN BIOMEDICINE 2009; 22:663-674. [PMID: 19378301 DOI: 10.1002/nbm.1387] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We describe a novel protocol for the non-histological diagnosis of human brain tumors in vitro combining high-resolution (31)P magnetic resonance spectroscopy ((31)P-MRS) of their phospholipid profile and statistical multivariate analysis. Chloroform/methanol extracts from 40 biopsies of human intracranial tumors obtained during neurosurgical procedures were prepared and analyzed by high-resolution (31)P-MRS. The samples were grouped in the following seven major classes: normal brain (n = 3), low-grade astrocytomas (n = 4), high-grade astrocytomas (n = 7), meningiomas (n = 9), schwannomas (n = 3), pituitary adenomas (n = 4), and metastatic tumors (n = 4). The phospholipid profile of every biopsy was determined by (31)P-NMR analysis of its chloroform/methanol extract and characterized by 19 variables including 10 individual phospholipid contributions and 9 phospholipid ratios. Most tumors depicted a decrease in phosphatidylethanolamine (PtdEtn) and phosphatidylserine (PtdSer), the former mainly in neuroepithelial neoplasms and the latter in metastases. An increase in phosphatidylcholine (PtdCho) and phosphatidylinositol (PtdIns) appeared predominantly in primary non-neuroepithelial tumors. Linear discriminant analysis (LDA) revealed the optimal combination of variables that could classify each biopsy between every pair of classes. The resultant discriminant functions were used to calculate the probability of correct classifications for each individual biopsy within the seven classes considered. Multilateral analysis classified correctly 100% of the normal brain samples, 89% of the meningiomas, 75% of the metastases, and 57% of the high-grade astrocytomas. The use of phospholipid profiles may complement appropriately previously proposed methods of intelligent diagnosis of human cerebral tumors.
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Affiliation(s)
- Juan Solivera
- Department of Neurosurgery, Hospital Universitario Reina Sofía, Córdoba, Spain.
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156
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Mencarelli C, Hammels C, Van Den Broeck J, Losen M, Steinbusch H, Revert F, Saus J, Hopkins DA, De Baets MH, Steinbusch HW, Martinez-Martinez P. The expression of the Goodpasture antigen-binding protein (ceramide transporter) in adult rat brain. J Chem Neuroanat 2009; 38:97-105. [PMID: 19555756 DOI: 10.1016/j.jchemneu.2009.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 06/11/2009] [Accepted: 06/12/2009] [Indexed: 11/25/2022]
Abstract
The Goodpasture antigen-binding protein (GPBP) plays a critical role in brain development. Knockdown of GPBP leads to loss of myelinated tracts in the central nervous system and to extensive apoptosis in the brain during early embryogenesis. GPBP was initially identified as a protein associated with the autoantigen in Goodpasture autoimmune syndrome, where it was shown to be a kinase that regulates type IV collagen organization. GPBP isoforms bind and transport ceramide from the endoplasmic reticulum to the Golgi apparatus and are therefore also known as ceramide transporters (CERT). Ceramide dysregulation is involved in autoimmunity and neurodegenerative disorders. In order to analyze the possible role of GPBP in neuroinflammation and neurodegeneration we studied the basal GPBP expression in normal rat brain. High levels of immunoreactivity were detected in neurons of the cerebral cortex, hippocampal formation, the basal ganglia, the olfactory bulb and nuclei of the thalamus, the hypothalamus and the septal area. Lower expression levels of GPBP were observed widely throughout the brain, suggesting that GPBP plays an important role in central nervous system neuron function.
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Affiliation(s)
- Chiara Mencarelli
- Department of Neuroscience, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
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157
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Goldfinger M, Laviad EL, Hadar R, Shmuel M, Dagan A, Park H, Merrill AH, Ringel I, Futerman AH, Tirosh B. De novo ceramide synthesis is required for N-linked glycosylation in plasma cells. THE JOURNAL OF IMMUNOLOGY 2009; 182:7038-47. [PMID: 19454701 DOI: 10.4049/jimmunol.0802990] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Plasma cells (PCs) are terminally differentiated B lymphocytes responsible for the synthesis and secretion of Igs. The differentiation of B cells into PCs involves a remarkable expansion of both lipid and protein components of the endoplasmic reticulum. Despite their importance in many signal transduction pathways, the role of ceramides, and of complex sphingolipids that are derived from ceramide, in PC differentiation has never been directly studied. To assess their putative role in PC differentiation, we blocked ceramide synthesis with fumonisin B1, a specific inhibitor of ceramide synthase. Under fumonisin B1 treatment, N-linked glycosylation was severely impaired in LPS-activated, but not in naive, B cells. We also show that ceramide synthesis is strongly induced by XBP-1 (X box-binding protein-1). In the absence of ceramide synthesis, ER expansion was dramatically diminished. Our results underscore ceramide biosynthesis as a key metabolic pathway in the process of PC differentiation and reveal a previously unknown functional link between sphingolipids and N-linked glycosylation in PCs.
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Affiliation(s)
- Meidan Goldfinger
- Department of Pharmacology and Experimental Therapeutics, School of Pharmacy, The Hebrew University, Jerusalem, Israel
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158
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Lin YC, Chou LC, Chen SC, Kuo SC, Huang LJ, Gean PW. Neuroprotective effects of furopyrazole derivative of benzylindazole analogs on C2 ceramide-induced apoptosis in cultured cortical neurons. Bioorg Med Chem Lett 2009; 19:3225-8. [DOI: 10.1016/j.bmcl.2009.04.101] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2009] [Revised: 04/20/2009] [Accepted: 04/22/2009] [Indexed: 11/29/2022]
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159
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Tran MA, Watts RJ, Robertson GP. Use of liposomes as drug delivery vehicles for treatment of melanoma. Pigment Cell Melanoma Res 2009; 22:388-99. [PMID: 19493316 DOI: 10.1111/j.1755-148x.2009.00581.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Melanoma is a progressive disease that claims many lives each year due to lack of therapeutics effective for the long-term treatment of patients. Currently, the best treatment option is early detection followed by surgical removal. Better melanoma therapies that are effectively delivered to tumors with minimal toxicity for patients are urgently needed. Nanotechnologies provide one approach to encapsulate therapeutic agents leading to improvements in circulation time, enhanced tumor uptake, avoidance of the reticulo-endothelial system, and minimization of toxicity. Liposomes in particular are a promising nanotechnology that can be used for more effective delivery of therapeutic agents to treat melanoma. Liposomes delivering chemotherapies, siRNA, asODNs, DNA, and radioactive particles are just some of the promising new nanotechnology based therapies under development for the treatment of melanoma that are discussed in this review.
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Affiliation(s)
- Melissa A Tran
- Departments of Pharmacology, The Pennsylvania State University College of Medicine, University Drive, Hershey, PA, USA
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160
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Boutet I, Jollivet D, Shillito B, Moraga D, Tanguy A. Molecular identification of differentially regulated genes in the hydrothermal-vent species Bathymodiolus thermophilus and Paralvinella pandorae in response to temperature. BMC Genomics 2009; 10:222. [PMID: 19439073 PMCID: PMC2689276 DOI: 10.1186/1471-2164-10-222] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Accepted: 05/13/2009] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Hydrothermal vents and cold seeps represent oases of life in the deep-sea environment, but are also characterized by challenging physical and chemical conditions. The effect of temperature fluctuations on vent organisms in their habitat has not been well explored, in particular at a molecular level, most gene expression studies being conducted on coastal marine species. In order to better understand the response of hydrothermal organisms to different temperature regimes, differentially expressed genes (obtained by a subtractive suppression hybridization approach) were identified in the mussel Bathymodiolus thermophilus and the annelid Paralvinella pandorae irlandei to characterize the physiological processes involved when animals are subjected to long term exposure (2 days) at two contrasting temperatures (10 degrees versus 20 degrees C), while maintained at in situ pressures. To avoid a potential effect of pressure, the experimental animals were initially thermally acclimated for 24 hours in a pressurized vessel. RESULTS For each species, we produced two subtractive cDNA libraries (forward and reverse) from sets of deep-sea mussels and annelids exposed together to a thermal challenge under pressure. RNA extracted from the gills, adductor muscle, mantle and foot tissue were used for B. thermophilus. For the annelid model, whole animals (small individuals) were used. For each of the four libraries, we sequenced 200 clones, resulting in 78 and 83 unique sequences in mussels and annelids (about 20% of the sequencing effort), respectively, with only half of them corresponding to known genes. Real-time PCR was used to validate differentially expressed genes identified in the corresponding libraries. Strong expression variations have been observed for some specific genes such as the intracellular hemoglobin, the nidogen protein, and Rab7 in P. pandorae, and the SPARC protein, cyclophilin, foot protein and adhesive plaque protein in B. thermophilus. CONCLUSION Our results indicate that mussels and worms are not responding in the same way to temperature variations. While the results obtained for the mussel B. thermophilus seem to indicate a metabolic depression (strong decrease in the level of mRNA expression of numerous genes) when temperature increased, the annelid P. pandorae mainly displayed a strong regulation of the mRNA encoding subunits and linkers of respiratory pigments and some proteins involved in membrane structure. In both cases, these regulations seem to be partly due to a possible cellular oxidative stress induced by the simulated thermal environment (10 degrees C to 20 degrees C). This work will serve as a starting point for studying the transcriptomic response of hydrothermal mussels and annelids in future experiments in response to thermal stress at various conditions of duration and temperature challenge.
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Affiliation(s)
- Isabelle Boutet
- CNRS, UMR 7144, Adaptation et Diversité en Milieu Marin, Station Biologique, de Roscoff, 29682 Roscoff, France
- UPMC Univ Paris 06, UMR 7144, Equipe Génétique et Adaptation en Milieu Extrême, Station Biologique de Roscoff, 29682 Roscoff, France
| | - Didier Jollivet
- CNRS, UMR 7144, Adaptation et Diversité en Milieu Marin, Station Biologique, de Roscoff, 29682 Roscoff, France
- UPMC Univ Paris 06, UMR 7144, Equipe Génétique et Adaptation en Milieu Extrême, Station Biologique de Roscoff, 29682 Roscoff, France
| | - Bruce Shillito
- UPMC Université Paris 6, UMR 7138, Systématique, Adaptation et Evolution, 75005 Paris, France
| | - Dario Moraga
- UMR CNRS 6539, Laboratoire des Sciences de l'Environnement Marin, Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, Place Nicolas Copernic, 29280 Plouzané, France
| | - Arnaud Tanguy
- CNRS, UMR 7144, Adaptation et Diversité en Milieu Marin, Station Biologique, de Roscoff, 29682 Roscoff, France
- UPMC Univ Paris 06, UMR 7144, Equipe Génétique et Adaptation en Milieu Extrême, Station Biologique de Roscoff, 29682 Roscoff, France
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161
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Lu CY, Li CC, Liu KL, Tsai CW, Lii CK, Chen HW. Docosahexaenoic acid down-regulates phenobarbital-induced cytochrome P450 2B1 gene expression in rat primary hepatocytes via the sphingomyelinase/ceramide pathway. J Nutr Biochem 2009; 21:338-44. [PMID: 19427778 DOI: 10.1016/j.jnutbio.2009.01.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Revised: 01/08/2009] [Accepted: 01/09/2009] [Indexed: 11/29/2022]
Abstract
Docosahexaenoic acid (DHA) regulates the expression of cytochrome P450 2B1 (CYP 2B1) in rat primary hepatocytes in response to xenobiotics. Ceramide, a lipid signaling molecule, is involved in various physiological processes and can be generated by the hydrolysis of sphingomyelin via sphingomyelinase (SMase). DHA activates SMase and increases ceramide formation in vitro. Ceramides differentially enhance adenylyl cyclase activity in vitro depending on the chain length of their fatty acids. In addition, the cAMP-dependent PKA pathway down-regulates CYP 2B1 expression induced by phenobarbital (PB). In the present study, we determined the effect of DHA on SMase transactivation and the downstream pathway in CYP 2B1 expression induced by PB. SMase was activated by DHA 2 h after treatment, and D609 (an SMase inhibitor) attenuated the inhibition of PB-induced CYP 2B1 expression by DHA. Ceramide formation reached a maximum 3 h after DHA administration. C2-ceramide dose-dependently inhibited PB-induced CYP 2B1 expression and increased intracellular cAMP concentrations. SQ22536 (an adenylyl cyclase inhibitor) and H89 (a PKA-specific inhibitor) partially reversed the inhibition of PB-induced CYP 2B1 expression by C2-ceramide. These results suggest that stimulation of SMase, generation of ceramide and activation of the cAMP-dependent PKA pathway are involved in the inhibition exerted by DHA.
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Affiliation(s)
- Chia-Yang Lu
- Department of Nutrition, Chung Shan Medical University, Taichung 40201, Taiwan
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162
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Nunn AV, Bell JD, Guy GW. Lifestyle-induced metabolic inflexibility and accelerated ageing syndrome: insulin resistance, friend or foe? Nutr Metab (Lond) 2009; 6:16. [PMID: 19371409 PMCID: PMC2678135 DOI: 10.1186/1743-7075-6-16] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 04/16/2009] [Indexed: 12/16/2022] Open
Abstract
The metabolic syndrome may have its origins in thriftiness, insulin resistance and one of the most ancient of all signalling systems, redox. Thriftiness results from an evolutionarily-driven propensity to minimise energy expenditure. This has to be balanced with the need to resist the oxidative stress from cellular signalling and pathogen resistance, giving rise to something we call 'redox-thriftiness'. This is based on the notion that mitochondria may be able to both amplify membrane-derived redox growth signals as well as negatively regulate them, resulting in an increased ATP/ROS ratio. We suggest that 'redox-thriftiness' leads to insulin resistance, which has the effect of both protecting the individual cell from excessive growth/inflammatory stress, while ensuring energy is channelled to the brain, the immune system, and for storage. We also suggest that fine tuning of redox-thriftiness is achieved by hormetic (mild stress) signals that stimulate mitochondrial biogenesis and resistance to oxidative stress, which improves metabolic flexibility. However, in a non-hormetic environment with excessive calories, the protective nature of this system may lead to escalating insulin resistance and rising oxidative stress due to metabolic inflexibility and mitochondrial overload. Thus, the mitochondrially-associated resistance to oxidative stress (and metabolic flexibility) may determine insulin resistance. Genetically and environmentally determined mitochondrial function may define a 'tipping point' where protective insulin resistance tips over to inflammatory insulin resistance. Many hormetic factors may induce mild mitochondrial stress and biogenesis, including exercise, fasting, temperature extremes, unsaturated fats, polyphenols, alcohol, and even metformin and statins. Without hormesis, a proposed redox-thriftiness tipping point might lead to a feed forward insulin resistance cycle in the presence of excess calories. We therefore suggest that as oxidative stress determines functional longevity, a rather more descriptive term for the metabolic syndrome is the 'lifestyle-induced metabolic inflexibility and accelerated ageing syndrome'. Ultimately, thriftiness is good for us as long as we have hormetic stimuli; unfortunately, mankind is attempting to remove all hormetic (stressful) stimuli from his environment.
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Affiliation(s)
- Alistair Vw Nunn
- Metabolic and Molecular Imaging Group, MRC Clinical Sciences Centre, Hammersmith Hospital, Imperial College London, Du Cane Road, London, W12 OHS, UK.
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163
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Safety studies of pseudo-ceramide SLE66. Part 3: Effects on embryo/fetal development in rats. Food Chem Toxicol 2009; 47:681-6. [DOI: 10.1016/j.fct.2008.11.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Revised: 11/01/2008] [Accepted: 11/11/2008] [Indexed: 12/25/2022]
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164
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Cornell TT, Hinkovska-Galcheva V, Sun L, Cai Q, Hershenson MB, Vanway S, Shanley TP. Ceramide-dependent PP2A regulation of TNFalpha-induced IL-8 production in respiratory epithelial cells. Am J Physiol Lung Cell Mol Physiol 2009; 296:L849-56. [PMID: 19286927 DOI: 10.1152/ajplung.90516.2008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
IL-8 is a key mediator in the pathophysiology of acute lung injury. TNFalpha stimulates IL-8 production in respiratory epithelial cells by activating both the NF-kappaB and MAP kinase pathways. The precise mechanism by which these pathways are downregulated to terminate IL-8 production remains unclear. We studied the regulatory role of the serine/threonine phosphatase, PP2A, on the signaling pathways involved in IL-8 production from respiratory epithelial cells. Inhibition of PP2A using okadaic acid or gene knockdown using siRNA resulted in an augmentation of TNFalpha-induced IL-8 production. We also found that PP2A inhibition resulted in prolonged activation of JNK, p38, and ERK resulting in both increased transcriptional activation of the IL-8 promoter and posttranscriptional stabilization of IL-8 mRNA. Because TNFalpha had been shown to activate ceramide accumulation, and separate studies had linked ceramide with activation of PP2A, we hypothesized the pathway of TNFalpha-inducing ceramide to activate PP2A comprised an endogenous regulatory pathway. Inhibition of the immediate sphingomyelinase-dependent pathway as well as the de novo synthesis pathway of ceramide production reduced serine/threonine phosphatase activity and augmented IL-8 production. These data suggest that ceramide plays a role in activating PP2A to terminate ongoing IL-8 production. In summary, our data suggest that in respiratory epithelium, TNFalpha induces ceramide accumulation, resulting in subsequent activation of PP2A, which targets those kinases responsible for transcriptional activation of IL-8.
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Affiliation(s)
- Timothy T Cornell
- Division of Pediatric Critical Care Medicine, C. S. Mott Children's Hospital, Ann Arbor, MI 48109-0243, USA.
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165
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Kawamura H, Tatei K, Nonaka T, Obinata H, Hattori T, Ogawa A, Kazama H, Hamada N, Funayama T, Sakashita T, Kobayashi Y, Nakano T, Izumi T. Ceramide induces myogenic differentiation and apoptosis in Drosophila Schneider cells. JOURNAL OF RADIATION RESEARCH 2009; 50:161-169. [PMID: 19346679 DOI: 10.1269/jrr.08122] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Cells exposed to genotoxic stress, such as ionizing radiation and DNA damaging reagents, either arrest the cell cycle to repair the genome, or undergo apoptosis, depending on the extent of the DNA damage. DNA damage also has been implicated in various differentiation processes. It has been reported that gamma-ray exposure or treatment with DNA-damaging agents could induce myogenic differentiation in Drosophila Schneider cells. However, the mechanism underlying this process has been poorly understood. In this study, exposure of Schneider cells to X-rays or energetic carbon ion beams caused increase of TUNEL-positive cells and conversion of round-shaped cells to elongated cells. Both upregulation of genes related to myogenesis and increase of myosin indicate that the radiation-induced morphological changes of Schneider cells were accompanied with myogenic differentiation. Because the intracellular ceramide was increased in Schneider cells after exposure to X-ray, we examined whether exogenous ceramide could mimic radiation-induced myogenic differentiation. Addition of membrane-permeable C(2)-ceramide to Schneider cells increased apoptosis and expression of myogenic genes. These results suggest that ceramide plays important roles in both apoptosis and the radiation-induced myogenic differentiation process.
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Affiliation(s)
- Hidemasa Kawamura
- Department of Radiation Oncology, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma, Japan
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166
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Bennaceur K, Popa I, Chapman JA, Migdal C, Péguet-Navarro J, Touraine JL, Portoukalian J. Different mechanisms are involved in apoptosis induced by melanoma gangliosides on human monocyte-derived dendritic cells. Glycobiology 2009; 19:576-82. [PMID: 19240275 PMCID: PMC2682607 DOI: 10.1093/glycob/cwp015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Tumor escape is linked to multiple mechanisms, notably the liberation, by tumor cells, of soluble factors that inhibit the function of dendritic cells (DC). We have shown that melanoma gangliosides impair DC differentiation and induce their apoptosis. The present study was aimed to give insight into the mechanisms involved. DC apoptosis was independent of the catabolism of gangliosides since lactosylceramide did not induce cell death. Apoptosis induced by GM3 and GD3 gangliosides was not blocked by inhibitors of de novo ceramide biosynthesis, whereas the acid sphingomyelinase inhibitor desipramine only prevented apoptosis induced by GM3. Furthermore, our results suggest that DC apoptosis was triggered via caspase activation, and it was ROS dependent with GD3 ganglioside, suggesting that GM3 and GD3 induced apoptosis through different mechanisms.
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Affiliation(s)
- Karim Bennaceur
- Laboratory of Dermatological Research, University of Lyon-1 EA 41-69, Edouard Herriot Hospital, Lyon, France.
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167
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Modulating serine palmitoyl transferase (SPT) expression and activity unveils a crucial role in lipid-induced insulin resistance in rat skeletal muscle cells. Biochem J 2009; 417:791-801. [PMID: 18922131 DOI: 10.1042/bj20081149] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Saturated fatty acids, such as palmitate, promote accumulation of ceramide, which impairs activation and signalling of PKB (protein kinase B; also known as Akt) to important end points such as glucose transport. SPT (serine palmitoyl transferase) is a key enzyme regulating ceramide synthesis from palmitate and represents a potential molecular target in curbing lipid-induced insulin resistance. In the present study we explore the effects of palmitate upon insulin action in L6 muscle cells in which SPT expression/activity has been decreased by shRNA (small-hairpin RNA) or sustained incubation with myriocin, an SPT inhibitor. Incubation of L6 myotubes with palmitate (for 16 h) increases intramyocellular ceramide and reduces insulin-stimulated PKB activation and glucose uptake. PKB inhibition was not associated with impaired IRS (insulin receptor substrate) signalling and was ameliorated by short-term treatment with myriocin. Silencing SPT expression (approximately 90%) by shRNA or chronic cell incubation with myriocin (for 7 days) markedly suppressed SPT activity and palmitate-driven ceramide synthesis; however, challenging these muscle cells with palmitate still inhibited the hormonal activation of PKB. This inhibition was associated with reduced IRS1/p85-PI3K (phosphoinositide 3-kinase) coupling that arises from diverting palmitate towards greater DAG (diacylglycerol) synthesis, which elevates IRS1 serine phosphorylation via activation of DAG-sensitive PKCs (protein kinase Cs). Treatment of SPT-shRNA cells or those treated chronically with myriocin with PKC inhibitors antagonized palmitate-induced loss in insulin signalling. The findings of the present study indicate that SPT plays a crucial role in desensitizing muscle cells to insulin in response to incubation with palmitate. While short-term inhibition of SPT ameliorates palmitate/ceramide-induced insulin resistance, sustained loss/reduction in SPT expression/activity promotes greater partitioning of palmitate towards DAG synthesis, which impacts negatively upon IRS1-directed insulin signalling.
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168
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Membrane lipid domains and rafts: current applications of fluorescence lifetime spectroscopy and imaging. Chem Phys Lipids 2009; 157:61-77. [DOI: 10.1016/j.chemphyslip.2008.07.011] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Accepted: 07/24/2008] [Indexed: 11/30/2022]
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169
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OHTA E, OHIRA T, MATSUE K, IKEDA Y, FUJII K, OHWAKI K, OSUKA S, HIRABAYASHI Y, SASAKI M. Analysis of Development of Lesions in Mice with Serine Palmitoyltransferase (SPT) Deficiency -Sptlc2 Conditional Knockout Mice-. Exp Anim 2009; 58:515-24. [DOI: 10.1538/expanim.58.515] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Affiliation(s)
- Etsuko OHTA
- Safety Assessment, Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd
- Drug Safety Research Laboratories, Eisai Co., Ltd
| | - Takashi OHIRA
- Safety Assessment, Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd
| | - Kenta MATSUE
- Safety Assessment, Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd
| | - Yuika IKEDA
- Metabolic Disorder Research, Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd
| | - Kenji FUJII
- Pharmacology, Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd
| | - Kenji OHWAKI
- Metabolic Disorder Research, Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd
| | - Sou OSUKA
- Research Unit, RIKEN Brain Science Institute
| | | | - Minoru SASAKI
- Safety Assessment, Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd
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170
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Loura LM, de Almeida RF, Silva LC, Prieto M. FRET analysis of domain formation and properties in complex membrane systems. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:209-24. [DOI: 10.1016/j.bbamem.2008.10.012] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2008] [Revised: 10/16/2008] [Accepted: 10/16/2008] [Indexed: 12/27/2022]
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171
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Błachnio-Zabielska A, Baranowski M, Zabielski P, Górski J. Effect of exercise duration on the key pathways of ceramide metabolism in rat skeletal muscles. J Cell Biochem 2008; 105:776-84. [PMID: 18680146 DOI: 10.1002/jcb.21877] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Ceramide is the key compound on crossroads of sphingolipid metabolism. The content and composition of ceramides in skeletal muscles have been shown to be affected by prolonged exercise. The aim of this study was to examine the effect of exercise on the activity of key enzymes of ceramide metabolism in skeletal muscles. The experiments were carried out on male Wistar rats (200-250 g) divided into four groups: sedentary, exercised for 30 min, 90 min, and until exhaustion. The activity of serine palmitoyltransferase (SPT), neutral and acid sphingomyelinase (nSMase and aSMase), neutral and alkaline ceramidases (nCDase and alCDase) and the content of ceramide, sphingosine, sphinganine and sphingosine-1-phosphate were determined in three types of muscle. We have found that the activity and expression of SPT increase gradually in each muscle with duration of exercise. These changes were followed by elevation in the content of sphinganine. These data indicate that exercise increases de novo synthesis of ceramide. The aSMase activity gradually decreased with duration of exercise in each type of muscle. After exhaustive exercise the activity of both isoforms of ceramidase were reduced in each muscle. The ceramide level depends both on duration of exercise and muscle type. The ceramide level in the soleus and white gastrocnemius decreased after 30 min of running. After exhaustive exercise it was elevated in the soleus and red gastrocnemius. It is concluded that exercise strongly affects the activity of key enzymes involved in ceramide metabolism and in consequence the level of sphingolipid intermediates in skeletal muscles.
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172
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Kim S, Kim Y, Lee Y, Chung JH. Ceramide accelerates ultraviolet-induced MMP-1 expression through JAK1/STAT-1 pathway in cultured human dermal fibroblasts. J Lipid Res 2008; 49:2571-81. [DOI: 10.1194/jlr.m800112-jlr200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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173
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Nica AF, Tsao CC, Watt JC, Jiffar T, Kurinna S, Jurasz P, Konopleva M, Andreeff M, Radomski MW, Ruvolo PP. Ceramide promotes apoptosis in chronic myelogenous leukemia-derived K562 cells by a mechanism involving caspase-8 and JNK. Cell Cycle 2008; 7:3362-70. [PMID: 18948750 DOI: 10.4161/cc.7.21.6894] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Ceramide is a sphingolipid that activates stress kinases such as p38 and c-JUN N-Terminal Kinase (JNK). Though Chronic Myelogenous Leukemia (CML) derived K562 cells resist killing by short chain C2-ceramide, we report here that longer chain C6-ceramide promotes apoptosis in these cells. C6-ceramide induces cleavage of Caspase-8 and Caspase-9, but only Caspase-8 is required for apoptosis. The sphingolipid killed CML derived KBM5 cells and, to a lesser extent, imatinib-resistant KBM5-STI cells suggesting that BCR-ABL can not completely block C6-ceramide-induced apoptosis but the kinase may regulate the process. BCR-ABL is known to suppress Protein Phosphatase 2A (PP2A) in CML cells. While C6-ceramide can activate PP2A in acute leukemia cells, the sphingolipid did not activate the phosphatase in K562 cells. C6-ceramide did not activate p38 kinase but did promote JNK activation and phosphorylation of JUN. Inhibition of JNK by pharmacological agent protected K562 cells from C6-ceramide suggesting that JNK plays an essential role in C6-ceramide mediated apoptosis. Furthermore, the sphingolipid promoted MCL-1 phosphorylation by a mechanism that, at least in part, involves JNK. The findings presented here suggest that Caspase-8, JNK, and perhaps MCL-1 may play important roles in regulating cell death and may represent new targets for therapeutic strategies for CML.
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Affiliation(s)
- Alina Felicia Nica
- Institute of Molecular Medicine, University of Texas Health Science Center, Houston, Texas, USA
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174
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Ceramide production associated with retinal apoptosis after retinal detachment. Graefes Arch Clin Exp Ophthalmol 2008; 247:215-24. [DOI: 10.1007/s00417-008-0957-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2008] [Revised: 09/13/2008] [Accepted: 09/22/2008] [Indexed: 10/21/2022] Open
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175
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Arboleda G, Morales LC, Benítez B, Arboleda H. Regulation of ceramide-induced neuronal death: cell metabolism meets neurodegeneration. ACTA ACUST UNITED AC 2008; 59:333-46. [PMID: 18996148 DOI: 10.1016/j.brainresrev.2008.10.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Revised: 10/09/2008] [Accepted: 10/13/2008] [Indexed: 12/14/2022]
Abstract
The present review explores the role of ceramides in neuronal apoptosis, as well as the recent discovery of the signaling pathways involved in this process placing particular emphasis on the correlation between cellular metabolism and neuronal death. Endogenous levels of ceramides are increased following various pro-apoptotic stimuli which have been identified as potential causes of chronic and acute neurodegenerative diseases. Ceramides induce changes in multiple enzymes and cell signaling components. The early inhibition of the neuronal survival pathway regulated by phosphatidil-inositol-3-kinase/protein kinase B or AKT mediated by ceramide may be a relevant early event in the decision of neuronal survival/death. It may perturb several molecular and metabolic functions. In particular it might decrease glycolysis through rapid modulation of hexokinase activity. This would in turn generate limited amounts of mitochondrial substrates leading to mitochondrial dysfunction and neuronal apoptosis. Subtle and early metabolic alterations caused by inhibition of the PI3K/AKT pathway mediated by ceramide may potentially work with genes associated with neurodegenerative diseases such as Parkinson's and Alzheimer's disease. Together they may be determinant steps in downstream events leading to neuronal apoptosis. Therefore, reinforcement of the PI3K/AKT pathway could constitute an important neuroprotective strategy.
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Affiliation(s)
- Gonzalo Arboleda
- Grupo de Neurociencias, Departamento de Patología, Facultad de Medicina, Universidad Nacional de Colombia, Bogotá, Colombia.
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176
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Corcoran CA, He Q, Ponnusamy S, Ogretmen B, Huang Y, Sheikh MS. Neutral sphingomyelinase-3 is a DNA damage and nongenotoxic stress-regulated gene that is deregulated in human malignancies. Mol Cancer Res 2008; 6:795-807. [PMID: 18505924 DOI: 10.1158/1541-7786.mcr-07-2097] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In this study, we report the characterization of a novel genotoxic and nongenotoxic stress-regulated gene that we had previously named as SKNY. Our results indicate that SKNY encodes the recently identified neutral sphingomyelinase-3 (nSMase3; hereafter SKNY is referred to as nSMase3). Examination of nSMase3 subcellular distribution reveals nSMase3 to localize to the endoplasmic reticulum (ER), and deletion of a COOH-terminal region containing its putative transmembrane domain and ER targeting signal partly alters its compartmentalization to the ER. Treatment with genotoxic Adriamycin and nongenotoxic tumor necrosis factor-alpha up-regulates endogenous nSMase3 expression, albeit with different kinetics. Tumor necrosis factor-alpha up-regulates nSMase3 expression within 2 h that lasts beyond 24 h and declines to control levels by 36 h. Adriamycin up-regulation of nSMase3 is transient, occurs within 30 min, and declines to control levels by 120 min. Prolonged treatment with Adriamycin by 24 h and beyond, however, causes a down-regulation in nSMase3 expression. Activation of wild-type p53 also down-regulates nSMase3 expression, suggesting that DNA damage-mediated nSMase3 down-regulation seems to occur partly through the tumor suppressor p53. Overexpression of exogenous nSMase3 sensitizes cells to Adriamycin-induced cell killing, a finding consistent with the proposed proapoptotic role of nSMase enzymes and nSMase-generated ceramide. We further investigated nSMase3 expression in various human malignancies and found its expression to be deregulated in several types of primary tumors when compared with their matching normal tissues. Collectively, our results have identified nSMase3 to be an important molecule that is linked to tumorigenesis and cellular stress response.
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Affiliation(s)
- Chad A Corcoran
- Department of Pharmacology, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA
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177
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Hu Y, Le Leu RK, Belobrajdic D, Young GP. The potential of sphingomyelin as a chemopreventive agent in AOM-induced colon cancer model: wild-type and p53+/- mice. Mol Nutr Food Res 2008; 52:558-66. [PMID: 18324704 DOI: 10.1002/mnfr.200700258] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A protective effect of sphingolipids on colorectal cancer (CRC) has been reported in certain mouse strains. It is unknown if sphingolipids are protective in a p53 deficiency mouse model of CRC. This study investigated the effect of sphingomyelin (SM) on intestinal sphingomyelinase (SMase) activity, colonic epithelial biology and azoxymethane (AOM)-induced CRC. Groups of wild-type (C57BL/6J) and p53+/- mice were fed 0.1% SM diet for 4 wk, administered a single AOM injection and then killed 6 h later to measure apoptosis and proliferation. Separately, both mouse types were fed 0.05% SM diet, administered three AOM injections and killed 33-38 wk later to measure tumour formation. SM significantly increased SMase activity and reduced proliferation (p < 0.05) in wild-type and p53+/- mice. SM did not regulate baseline apoptosis, apoptotic response to AOM or apoptosis in tumours, nor did it restore defective apoptosis in p53+/- mice. There was a nonsignificant trend to reduced tumour incidence with SM in wild-type (p = 0.15) and p53+/- (p = 0.12) mice. In conclusion, while increasing intestinal SMase activity and suppressing proliferation, SM did not promote any form of apoptosis and failed to achieve significant protection in these mice. Further investigation to understand the variable effect of SM in preventing CRC is warranted.
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Affiliation(s)
- Ying Hu
- Department of Medicine, Flinders University of South Australia, Bedford Park, Australia.
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178
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Nino-Fong R, Collins T, Chan C. Nutrigenomics, beta-cell function and type 2 diabetes. Curr Genomics 2008; 8:1-29. [PMID: 18645625 PMCID: PMC2474685 DOI: 10.2174/138920207780076947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Revised: 08/12/2006] [Accepted: 10/13/2006] [Indexed: 01/15/2023] Open
Abstract
INTRODUCTION The present investigation was designed to investigate the accuracy and precision of lactate measurement obtained with contemporary biosensors (Chiron Diagnostics, Nova Biomedical) and standard enzymatic photometric procedures (Sigma Diagnostics, Abbott Laboratories, Analyticon). MATERIALS AND METHODS Measurements were performed in vitro before and after the stepwise addition of 1 molar sodium lactate solution to samples of fresh frozen plasma to systematically achieve lactate concentrations of up to 20 mmol/l. RESULTS Precision of the methods investigated varied between 1% and 7%, accuracy ranged between 2% and -33% with the variability being lowest in the Sigma photometric procedure (6%) and more than 13% in both biosensor methods. CONCLUSION Biosensors for lactate measurement provide adequate accuracy in mean with the limitation of highly variable results. A true lactate value of 6 mmol/l was found to be presented between 4.4 and 7.6 mmol/l or even with higher difference. Biosensors and standard enzymatic photometric procedures are only limited comparable because the differences between paired determinations presented to be several mmol. The advantage of biosensors is the complete lack of preanalytical sample preparation which appeared to be the major limitation of standard photometry methods.
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Affiliation(s)
- R Nino-Fong
- Department of Biomedical Sciences, University of Prince Edward Island, Charlottetown, PE C1A 4P3 Canada
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179
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Zhang C. The role of inflammatory cytokines in endothelial dysfunction. Basic Res Cardiol 2008; 103:398-406. [PMID: 18600364 DOI: 10.1007/s00395-008-0733-0] [Citation(s) in RCA: 328] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2008] [Accepted: 06/04/2008] [Indexed: 02/02/2023]
Abstract
Clinical and experimental data support a link between endothelial dysfunction and inflammation. Inflammatory cytokines are important protagonists in formation of atherosclerotic plaque, eliciting effects throughout the atherosclerotic vessel. Importantly, the development of atherosclerotic lesions, regardless of the risk factor, e.g., diabetes, hypertension, obesity, is characterized by disruption in normal function of the endothelial cells. Endothelial cells, which line the internal lumen of the vasculature, are part of a complex system that regulates vasodilation and vasoconstriction, growth of vascular smooth muscle cells, inflammation, and hemostasis, maintaining a proper blood supply to tissues and regulating inflammation and coagulation. Current concepts suggest that the earliest event in atherogenesis is endothelial dysfunction, manifested by deficiencies in the production of nitric oxide (NO) and prostacyclin. The focus of this review is to summarize recent evidence showing the effects of inflammation on vascular dysfunction in ischemic-heart disease, which may prompt new directions for targeting inflammation in future therapies.
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Affiliation(s)
- Cuihua Zhang
- Department of Internal Medicine, University of Missouri, Columbia, MO 65211, USA.
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180
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Affiliation(s)
- Romain Harmancey
- Department of Internal Medicine, Division of Cardiology, University of Texas Medical School at Houston, 6431 Fannin, MSB 1.246, Houston, TX 77030, USA
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181
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von Bismarck P, García Wistädt CF, Klemm K, Winoto-Morbach S, Uhlig U, Schütze S, Adam D, Lachmann B, Uhlig S, Krause MF. Improved Pulmonary Function by Acid Sphingomyelinase Inhibition in a Newborn Piglet Lavage Model. Am J Respir Crit Care Med 2008; 177:1233-41. [DOI: 10.1164/rccm.200705-752oc] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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182
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Abstract
Glucotoxicity, lipotoxicity, and glucolipotoxicity are secondary phenomena that are proposed to play a role in all forms of type 2 diabetes. The underlying concept is that once the primary pathogenesis of diabetes is established, probably involving both genetic and environmental forces, hyperglycemia and very commonly hyperlipidemia ensue and thereafter exert additional damaging or toxic effects on the beta-cell. In addition to their contribution to the deterioration of beta-cell function after the onset of the disease, elevations of plasma fatty acid levels that often accompany insulin resistance may, as glucose levels begin to rise outside of the normal range, also play a pathogenic role in the early stages of the disease. Because hyperglycemia is a prerequisite for lipotoxicity to occur, the term glucolipotoxicity, rather than lipotoxicity, is more appropriate to describe deleterious effects of lipids on beta-cell function. In vitro and in vivo evidence supporting the concept of glucotoxicity is presented first, as well as a description of the underlying mechanisms with an emphasis on the role of oxidative stress. Second, we discuss the functional manifestations of glucolipotoxicity on insulin secretion, insulin gene expression, and beta-cell death, and the role of glucose in the mechanisms of glucolipotoxicity. Finally, we attempt to define the role of these phenomena in the natural history of beta-cell compensation, decompensation, and failure during the course of type 2 diabetes.
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Affiliation(s)
- Vincent Poitout
- Montreal Diabetes Research Center, CR-CHUM, Technopole Angus, 2901 Rachel Est, Montreal, Quebec, Canada H1W 4A4.
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183
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Ceramide induces p38 MAPK and JNK activation through a mechanism involving a thioredoxin-interacting protein-mediated pathway. Blood 2008; 111:4365-74. [PMID: 18270325 DOI: 10.1182/blood-2007-08-106336] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Ceramide, a tumor-suppressor lipid, is generated by sphingomyelin hydrolysis or by de novo synthesis when cells are activated by various stress stimuli as well as when cancer cells are subjected to genotoxic chemotherapy. Ceramide may modulate apoptotic signaling pathways; however, its transcription-dependent effects remain unclear. Our data showed that actinomycin D partially inhibited ceramide-induced apoptosis. Using microarray analysis, we found that ceramide up-regulated a tumor suppressor gene called thioredoxin-interacting protein (Txnip). Similarly, the chemotherapeutic agent etoposide induced Txnip expression en route to apoptosis, which was blocked by inhibitors of ceramide production. Txnip colocalized with thioredoxin and reduced its activity, which caused dissociation of thioredoxin from apoptosis signal-regulating kinase 1 (ASK1). Cells expressing ASK1 siRNA were more resistant to ceramide-induced apoptosis. Ceramide caused ASK1-regulated p38 mitogen-activated protein kinase (MAPK) and JNK activation, as well as activation of the endoplasmic reticulum (ER) stress cascade, and pharmacologic or siRNA-mediated inhibition of p38 MAPK or JNK partially reduced ceramide-induced mitochondria-mediated apoptosis. Furthermore, ceramide-induced ASK1, p38, and JNK phosphorylation and cell apoptosis were inhibited by Txnip siRNA transfection. Taken together, we show that ceramide exhibits a mechanism of transcriptional regulation involving up-regulation of Txnip expression, also induced by etoposide, which results in ASK1 activation, ER stress, and p38 and JNK phosphorylation, all leading to apoptosis.
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184
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Charruyer A, Bell SM, Kawano M, Douangpanya S, Yen TY, Macher BA, Kumagai K, Hanada K, Holleran WM, Uchida Y. Decreased ceramide transport protein (CERT) function alters sphingomyelin production following UVB irradiation. J Biol Chem 2008; 283:16682-92. [PMID: 18411267 DOI: 10.1074/jbc.m800799200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Increased cellular ceramide accounts in part for UVB irradiation-induced apoptosis in cultured human keratinocytes with concurrent increased glucosylceramide but not sphingomyelin generation in these cells. Given that conversion of ceramide to non-apoptotic metabolites such as sphingomyelin and glucosylceramide protects cells from ceramide-induced apoptosis, we hypothesized that failed up-regulation of sphingomyelin generation contributes to ceramide accumulation following UVB irradiation. Because both sphingomyelin synthase and glucosylceramide synthase activities were significantly decreased in UVB-irradiated keratinocytes, we investigated whether alteration(s) in the function of ceramide transport protein (or CERT) required for sphingomyelin synthesis occur(s) in UVB-irradiated cells. Fluorescently labeled N-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-d-erythro-sphingosine (C(5)-DMB-ceramide) relocation to the Golgi was diminished after irradiation, consistent with decreased CERT function, whereas the CERT inhibitor N-(3-hydroxy-1-hydroxymethyl-3-phenylpropyl)dodecanamide (1R,3R isomer) (HPA-12) produced an equivalent effect. UVB irradiation also induced the rapid formation of a stable CERT homotrimer complex in keratinocytes as determined by Western immunoblot and mass spectrometry analyses, a finding replicated in HeLa, HEK293T, and HaCaT cells and in murine epidermis. Ceramide binding activity was decreased in recombinant CERT proteins containing the UVB-induced homotrimer. The middle region domain of the CERT protein was required for the homotrimer formation, whereas neither the pleckstrin homology (Golgi-binding) nor the START (ceramide-binding) domains were involved. Finally like UVB-treated keratinocytes, HPA-12 blockade of CERT function increased keratinocyte apoptosis, decreased sphingomyelin synthesis, and led to accumulation of ceramide. Thus, UVB-induced CERT homotrimer formation accounts, at least in part, for apoptosis and failed up-regulation of sphingomyelin synthesis following UVB irradiation, revealing that inactive CERT can attenuate a key metabolic protective mechanism against ceramide-induced apoptosis in keratinocytes.
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Affiliation(s)
- Alexandra Charruyer
- Department of Dermatology, School of Medicine, University of California, Northern California Institute for Research and Education, and Veterans Affairs Medical Center, San Francisco, California 94121, USA
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185
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Maines LW, Fitzpatrick LR, French KJ, Zhuang Y, Xia Z, Keller SN, Upson JJ, Smith CD. Suppression of ulcerative colitis in mice by orally available inhibitors of sphingosine kinase. Dig Dis Sci 2008; 53:997-1012. [PMID: 18058233 PMCID: PMC2660406 DOI: 10.1007/s10620-007-0133-6] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 04/28/2006] [Indexed: 01/06/2023]
Abstract
A critical step in the mechanism of action of inflammatory cytokines is the stimulation of sphingolipid metabolism, including activation of sphingosine kinase (SK), which produces the mitogenic and proinflammatory lipid sphingosine 1-phosphate (S1P). We have developed orally bioavailable compounds that effectively inhibit SK activity in vitro in intact cells and in cancer models in vivo. In this study, we assessed the effects of these SK inhibitors on cellular responses to tumor necrosis factor alpha (TNFalpha) and evaluated their efficacy in the dextran sulfate sodium (DSS) model of ulcerative colitis in mice. Using several cell systems, it was shown that the SK inhibitors block the ability of TNFalpha to activate nuclear factor kappa B (NFkappaB), induce expression of adhesion proteins, and promote production of prostaglandin E(2) (PGE(2)). In an acute model of DSS-induced ulcerative colitis, SK inhibitors were equivalent to or more effective than Dipentum in reducing disease progression, colon shortening, and neutrophil infiltration into the colon. The effects of SK inhibitors were associated with decreased colonic levels of inflammatory cytokines TNFalpha, interleukin (IL)-1beta, interferon gamma (IFN)-gamma, IL-6, and reduction of S1P levels. A similar reduction in disease progression was provided by SK inhibitors in a chronic model of ulcerative colitis in which the mice received 3-week-long cycles of DSS interspaced with week-long recovery periods. In the chronic model, immunohistochemistry for SK showed increased expression in DSS-treated mice (compared with water-treated controls) that was reduced by drug treatment. S1P levels were also elevated in the DSS group and significantly reduced by drug treatment. Together, these data indicate that SK is a critical component in inflammation and that inhibitors of this enzyme may be useful in treating inflammatory bowel diseases.
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Affiliation(s)
- Lynn W Maines
- Apogee Biotechnology Corporation, PO Box 916, Hershey, PA 17033, USA.
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186
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Xing YX, Li P, Miao YX, Du W, Wang CB. Involvement of ROS/ASMase/JNK signalling pathway in inhibiting UVA-induced apoptosis of HaCaT cells by polypeptide from Chlamys farreri. Free Radic Res 2008; 42:12-9. [PMID: 18324519 DOI: 10.1080/10715760701762415] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Polypeptide from Chlamys farreri (PCF), a novel marine active material isolated from gonochoric Chinese scallop C. farreri, has potential antioxidant activity and protective effect against ultraviolet (UV) irradiation. The aim was to investigate whether PCF protects HaCaT cells from apoptosis induced by UVA and explore related molecular mechanisms. The results showed that PCF significantly prevented UVA-induced apoptosis of HaCaT cells. PCF not only strongly reduced the intracellular reactive oxygen species (ROS) production, but also diminished expression of acid sphingomyelinase (ASMase) and phosphorylated JNK in HaCaT cells radiated by UVA in a dose-dependent manner. Pre-treatment with ROS scavenger NAC, ASMase inhibitor desipramine or JNK inhibitor SP600125 was found to effectively prohibit UVA-induced apoptosis and desipramine markedly blocked phosphorylation of JNK. So it is concluded that PCF obviously protects HaCaT cells from apoptosis induced by UVA and protective effects may attribute to decreasing intracellular ROS level and blocking ASMase/JNK apoptotic signalling pathway.
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Affiliation(s)
- Yan-Xia Xing
- Department of Biochemistry and Molecular Biology, Medical College of Qingdao University, Qingdao, China
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187
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Targeting of PKCzeta and PKB to caveolin-enriched microdomains represents a crucial step underpinning the disruption in PKB-directed signalling by ceramide. Biochem J 2008; 410:369-79. [PMID: 17983354 DOI: 10.1042/bj20070936] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Elevated ceramide concentrations in adipocytes and skeletal muscle impair PKB (protein kinase B; also known as Akt)-directed insulin signalling to key hormonal end points. An important feature of this inhibition involves the ceramide-induced activation of atypical PKCzeta (protein kinase C-zeta), which associates with and negatively regulates PKB. In the present study, we demonstrate that this inhibition is critically dependent on the targeting and subsequent retention of PKCzeta-PKB within CEM (caveolin-enriched microdomains), which is facilitated by kinase interactions with caveolin. Ceramide also recruits PTEN (phosphatase and tensin homologue detected on chromosome 10), a 3'-phosphoinositide phosphatase, thereby creating a repressive membrane microenvironment from which PKB cannot signal. Disrupting the structural integrity of caveolae by cholesterol depletion prevented caveolar targeting of PKCzeta and PKB and suppressed kinase-caveolin association, but, importantly, also ameliorated ceramide-induced inhibition of PKB. Consistent with this, adipocytes from caveolin-1-/- mice, which lack functional caveolae, exhibit greater resistance to ceramide compared with caveolin-1+/+ adipocytes. We conclude that the recruitment and retention of PKB within CEM contribute significantly to ceramide-induced inhibition of PKB-directed signalling.
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188
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Belkhiri A, Dar AA, Zaika A, Kelley M, El-Rifai W. t-Darpp promotes cancer cell survival by up-regulation of Bcl2 through Akt-dependent mechanism. Cancer Res 2008; 68:395-403. [PMID: 18199533 DOI: 10.1158/0008-5472.can-07-1580] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
t-Darpp is a cancer-related truncated isoform of Darpp-32 (dopamine and cyclic-AMP-regulated phosphoprotein of M(r) 32,000). We detected overexpression of t-Darpp mRNA in two thirds of gastric cancers compared with normal samples (P = 0.004). Using 20 micromol/L ceramide treatment as a model for induction of apoptosis in AGS cancer cells, we found that expression of t-Darpp led to an increase in Bcl2 protein levels and blocked the activation of caspase-3 and caspase-9. The MitoCapture mitochondrial apoptosis and cytochrome c release assays indicated that t-Darpp expression enforces the mitochondrial transmembrane potential and protects against ceramide-induced apoptosis. Interestingly, the expression of t-Darpp in AGS cells led to >or=2-fold increase in Akt kinase activity with an increase in protein levels of p-Ser(473) Akt and p-Ser(9) GSK3 beta. These findings were further confirmed using tetracycline-inducible AGS cells stably expressing t-Darpp. We also showed transcriptional up-regulation of Bcl2 using the luciferase assay with Bcl2 reporter containing P1 full promoter, quantitative reverse transcription-PCR, and t-Darpp small interfering RNA. The Bcl2 promoter contains binding sites for cyclic AMP-responsive element binding protein CREB/ATF1 transcription factors and using the electrophoretic mobility shift assay with a CREB response element, we detected a stronger binding in t-Darpp-expressing cells. The t-Darpp expression led to an increase in expression and phosphorylation of CREB and ATF-1 transcription factors that were required for up-regulating Bcl2 levels. Indeed, knockdown of Akt, CREB, or ATF1 in t-Darpp-expressing cells reduced Bcl2 protein levels. In conclusion, the t-Darpp/Akt axis underscores a novel oncogenic potential of t-Darpp in gastric carcinogenesis and resistance to drug-induced apoptosis.
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Affiliation(s)
- Abbes Belkhiri
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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189
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Sabourdy F, Kedjouar B, Sorli SC, Colié S, Milhas D, Salma Y, Levade T. Functions of sphingolipid metabolism in mammals--lessons from genetic defects. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1781:145-83. [PMID: 18294974 DOI: 10.1016/j.bbalip.2008.01.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2007] [Revised: 01/15/2008] [Accepted: 01/15/2008] [Indexed: 01/23/2023]
Abstract
Much is known about the pathways that control the biosynthesis, transport and degradation of sphingolipids. During the last two decades, considerable progress has been made regarding the roles this complex group of lipids play in maintaining membrane integrity and modulating responses to numerous signals. Further novel insights have been provided by the analysis of newly discovered genetic diseases in humans as well as in animal models harboring mutations in the genes whose products control sphingolipid metabolism and action. Through the description of the phenotypic consequences of genetic defects resulting in the loss of activity of the many proteins that synthesize, transport, bind, or degrade sphingolipids, this review summarizes the (patho)physiological functions of these lipids.
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190
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Liu YY, Yu JY, Yin D, Patwardhan GA, Gupta V, Hirabayashi Y, Holleran WM, Giuliano AE, Jazwinski SM, Gouaze-Andersson V, Consoli DP, Cabot MC. A role for ceramide in driving cancer cell resistance to doxorubicin. FASEB J 2008; 22:2541-51. [PMID: 18245173 DOI: 10.1096/fj.07-092981] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Advanced cancers acquire resistance to chemotherapy, and this results in treatment failure. The cellular mechanisms of chemotherapy resistance are not well understood. Here, for the first time, we show that ceramide contributes to cellular resistance to doxorubicin through up-regulating the gene expression of glucosylceramide synthase (GCS). Ceramide, a cellular lipid messenger, modulates doxorubicin-induced cell death. GCS catalyzes ceramide glycosylation, converting ceramide to glucosylceramide; this process hastens ceramide clearance and limits ceramide-induced apoptosis. In the present study, we evaluated the role of the GCS gene in doxorubicin resistance using several paired wild-type and drug-resistant (doxorubicin-selected) cancer cell lines, including breast, ovary, cervical, and colon. GCS was overexpressed in all drug-resistant counterparts, and suppressing GCS overexpression using antisense oligonucleotide restored doxorubicin sensitivity. Characterizing the effect mechanism showed that doxorubicin exposure increased ceramide levels, enhanced GCS expression, and imparted cellular resistance. Exogenous C(6)-ceramide and sphingomyelinase treatments mimicked the influence of doxorubicin on GCS, activating the GCS promoter and up-regulating GCS gene expression. Fumonisin B(1), an inhibitor of ceramide synthesis, significantly suppressed doxorubicin-up-regulated GCS expression. Promoter truncation, point mutation, gel-shift, and protein-DNA ELISA analysis showed that transcription factor Sp1 was essential for ceramide-induced GCS up-regulation. These data indicate that ceramide-governed GCS gene expression drives cellular resistance to doxorubicin.
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Affiliation(s)
- Yong-Yu Liu
- Department of Basic Pharmaceutical Sciences, University of Louisiana at Monroe, 700 University Ave., Monroe, LA 71209, USA.
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191
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Abstract
Chilling injury is the major limiting factor for successful cryopreservation of both human and animal oocytes. Maternal hyperthermia is the main reason for summer infertility in dairy cows. In this paper, we will present evidence for the involvement of membrane lipid composition and its thermotrophic behavior and the mechanism by which chilling injury and/or heat stress disrupt oocytes' developmental competence. Although oocyte and single zygote are similar in shape and size, the oocyte is known to be very sensitive to cryopreservation, whereas, the zygote is successfully cryopreserved. Recently, we have shown that the lipid-phase transition (LPT) in human MII oocytes occurs at about 20 degrees C, while the LPT temperature of zygotes is lower by 10 degrees C. Similarly, the LPT in oocytes collected from dairy cows was found to be elevated by 10 degrees C in the summer vs. the winter. This feature was associated with alterations in membrane lipid composition. In particular, during the winter, the oocyte membrane is composed mainly of mono- and polyunsaturated fatty acids while in the hot summer, it is composed of more saturated fatty acids. In another study, we showed that exposure of bovine oocytes to physiologically relevant heat shock increases the proportion of oocytes that undergo apoptosis, presumably via sphingomyelin hydrolysis and ceramide formation (i.e. the sphingomyelin apoptosis pathway). Using a mouse model, we have recently shown that hyperthermia of 1.5 degrees C affects the follicle enclosed oocyte as determined by lower developmental competence. Given the importance of the membrane's composition and integrity, it appears that alterations in the oocyte-membrane underlie the disruption of developmental competence in mammalian oocytes exposed to thermal stress (i.e. chilling injury or heat shock).
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Affiliation(s)
- Amir Arav
- Institute of Animal Science, Agricultural Research Organization, the Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel.
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192
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Babenko NA, Shakhova EG. Effects of flavonoids on sphingolipid turnover in the toxin-damaged liver and liver cells. Lipids Health Dis 2008; 7:1. [PMID: 18226198 PMCID: PMC2265705 DOI: 10.1186/1476-511x-7-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Accepted: 01/28/2008] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The ceramide generation is an early event in the apoptotic response to numerous stimuli including the oxidative stress and ceramide analogs mimic the stress effect and induce apoptosis. Flavonoids of German chamomile are reported to exhibit the hepatoprotective effect. Flavonoids affect sphingolipid metabolism and reduce the elevated ceramide level in the aged liver. In the present paper, the ceramide content and production in the CCl4- and ethanol-treated liver and hepatocytes as well as the correction of sphingolipid metabolism in the damaged liver using the mixture of German chamomile flavonoids (chamiloflan) or apigenin-7-glucoside (AP7Glu) have been investigated. RESULTS The experiments were performed in either the rat liver or hepatocytes of normal, CCl4- and ethanol-treated or flavonoid- and toxin plus flavonoid-treated animals. [14C]palmitic acid and [methyl-14C-phosphorylcholine]sphingomyelin were used to investigate the sphingolipid turnover. Addition of the CCl4 or ethanol to isolated hepatocyte suspensions caused loss of cell viability and increased the lactate dehydrogenase release from the cells into supernatant and ceramide level in the cells. CCl4 administration to the rats enlarged ceramide mass as well as neutral sphingomyelinase (SMase) activity and reduced ceramide degradation by the neutral ceramidase. Pretreatment of isolated hepatocytes with flavonoids abrogated the CCl4 effects on the cell membrane integrity and normalized the ceramide content. Flavonoid administration to the rats normalized the elevated ceramide content in the damaged liver via neutral SMase inhibition and ceramidase activation. CONCLUSION The data obtained have demonstrated that flavonoids affect sphingolipid metabolism in the CCl4- and ethanol-damaged liver and liver cells. Flavonoids normalized activities of key enzymes of sphingolipid turnover (neutral SMase and ceramidase) and ceramide contents in the damaged liver and liver cells, and stabilized the hepatocyte membranes.
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Affiliation(s)
- Nataliya A Babenko
- Department of Physiology of Ontogenesis, Institute of Biology, Kharkov Karazin National University, 4, Svobody pl., Kharkov, 61077, Ukraine
| | - Elena G Shakhova
- Department of Physiology of Ontogenesis, Institute of Biology, Kharkov Karazin National University, 4, Svobody pl., Kharkov, 61077, Ukraine
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193
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Reinehr R, Sommerfeld A, Keitel V, Grether-Beck S, Häussinger D. Amplification of CD95 Activation by Caspase 8-induced Endosomal Acidification in Rat Hepatocytes. J Biol Chem 2008; 283:2211-22. [DOI: 10.1074/jbc.m706853200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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194
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Cell Structure, Function, and Genetics. Surgery 2008. [DOI: 10.1007/978-0-387-68113-9_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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195
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Johnny S, Liana, C. S, Anthony, H. F. Ceramide-containing membranes: the interface between biophysics and biology. TRENDS GLYCOSCI GLYC 2008. [DOI: 10.4052/tigg.20.297] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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196
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Hatch GM, Gu Y, Xu FY, Cizeau J, Neumann S, Park JS, Loewen S, Mowat MRA. StARD13(Dlc-2) RhoGap mediates ceramide activation of phosphatidylglycerolphosphate synthase and drug response in Chinese hamster ovary cells. Mol Biol Cell 2007; 19:1083-92. [PMID: 18162584 DOI: 10.1091/mbc.e06-08-0737] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
To identify genes involved in etoposide drug response, we used promoter trap mutagenesis to isolate an etoposide-resistant Chinese hamster ovary (CHO) cell line. This resistant CHO-K1 line, named E91, showed cross-resistance to C(2)-ceramide (N-acetylsphingosine). The promoter trap retrovirus was found integrated into intron 1-2 of the Dlc-2 (Stard13) RhoGap gene. The E91 cells showed elevated guanosine triphosphate (GTP)-bound RhoA levels compared with the parental line, suggesting that retrovirus integration had inactivated one of the Dlc-2 RhoGap alleles. To test whether E91 cells were impaired in an intracellular ceramide-regulated process not directly related to cell killing, we measured mitochondrial phosphatidylglycerolphosphate (PGP) synthase and phospholipase A2 enzyme activities in cells after C(2)-ceramide addition. Parental cells showed elevated enzyme activities after treatment with C(2)-ceramide or tumor necrosis factor alpha, but not the E91 cells. These results suggested that intracellular ceramide signaling was defective in E91 cells due to increased levels of active GTP-bound RhoA. RNA knockdown experiments of the Dlc2 RhoGap resulted in increased GTP-bound RhoA and reduced induction of PGP synthase after C(2)-ceramide addition compared with controls. Expression of a dominant-negative RhoA in the E91 cell line allowed induction of PGP synthase by ceramide. The RNA interference knockdown cell line also showed increased etoposide resistance. This study is the first report for the regulation of a phospholipid biosynthetic enzyme through RhoGap expression.
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Affiliation(s)
- Grant M Hatch
- Manitoba Institute of Cell Biology, CancerCare Manitoba, Winnipeg, Manitoba, Canada R3E 0V9
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197
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Arai N, Masuzaki H, Tanaka T, Ishii T, Yasue S, Kobayashi N, Tomita T, Noguchi M, Kusakabe T, Fujikura J, Ebihara K, Hirata M, Hosoda K, Hayashi T, Sawai H, Minokoshi Y, Nakao K. Ceramide and adenosine 5'-monophosphate-activated protein kinase are two novel regulators of 11beta-hydroxysteroid dehydrogenase type 1 expression and activity in cultured preadipocytes. Endocrinology 2007; 148:5268-77. [PMID: 17702848 DOI: 10.1210/en.2007-0349] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Increased activity of intracellular glucocorticoid reactivating enzyme, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) in obese adipose tissue contributes to adipose dysfunction. As recent studies have highlighted a potential role of preadipocytes in adipose dysfunction, we tested the hypothesis that a variety of metabolic stress mediated by ceramide or AMP-activated protein kinase (AMPK) would regulate 11beta-HSD1 in preadipocytes. The present study is the first to show that 1) expression of 11beta-HSD1 in 3T3-L1 preadipocytes was robustly induced when cells were treated with cell-permeable ceramide analogue C(2) ceramide, bacterial sphingomyelinase, and sphingosine 1-phosphate, 2) 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR)-induced activation of AMPK augmented the expression and enzyme activity of 11beta-HSD1, and 3) these results were reproduced in human preadipocytes. We demonstrate for the first time that C(2) ceramide and AICAR markedly induced the expression of CCAAT/enhancer-binding protein (C/EBP) beta and its binding to 11beta-HSD1 promoter. Transient knockdown of C/EBPbeta protein by small interfering RNA markedly attenuated the expression of 11beta-HSD1 induced by C(2) ceramide or AICAR. The present study provides novel evidence that ceramide- and AMPK-mediated signaling pathways augment the expression and activity of 11beta-HSD1 in preadipocytes by way of C/EBPbeta, thereby highlighting a novel, metabolic stress-related regulation of 11beta-HSD1 in a cell-specific manner.
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Affiliation(s)
- N Arai
- Division of Endocrinology and Metabolism, Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, Kyoto, Japan
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198
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Ceramide: a common pathway for atherosclerosis? Atherosclerosis 2007; 196:497-504. [PMID: 17963772 DOI: 10.1016/j.atherosclerosis.2007.09.018] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2007] [Revised: 09/08/2007] [Accepted: 09/13/2007] [Indexed: 10/22/2022]
Abstract
Plasma sphingomyelin concentration is correlated with the development of atherosclerosis. It has been found to exist in significantly higher concentrations in aortic plaque. This appears to have clinical relevance as well as it has been shown to be an independent predictor of coronary artery disease. Ceramide, the backbone of sphingolipids, is the key component which affects atherosclerotic changes through its important second-messenger role. This paper sheds light on some of the current literature supporting the significance of ceramide with respect to its interactions with lipids, inflammatory cytokines, homocysteine and matrix metalloproteinases. Furthermore, the potential therapeutic implications of modulating ceramide concentrations are also discussed.
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199
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Ortner E, Moelling K. Heteromeric complex formation of ASK2 and ASK1 regulates stress-induced signaling. Biochem Biophys Res Commun 2007; 362:454-9. [PMID: 17714688 DOI: 10.1016/j.bbrc.2007.08.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 08/01/2007] [Indexed: 11/17/2022]
Abstract
Apoptosis signal-regulating kinase 2 (ASK2) is an interaction partner of the highly related ASK1. Here, we describe a regulatory function of ASK2 in stress signaling-induced cleavage of caspase-3 and poly(ADP-ribose) polymerase (PARP). Increased cleavage of caspase-3 and PARP was demonstrated by overexpression as well as knockdown of ASK2 after stress-induction by serum-starvation. We show that ectopically expressed ASK2 homo-oligomerized while endogenous ASK2 and ASK1 formed hetero-oligomers, which decreased upon serum-starvation. Co-expression of ASK2 and ASK1 stabilized these two proteins and reduced starvation-induced caspase-3 activation and degradation of PARP. Analysis of the intracellular localization of ASK2 exhibited a similar localization compared with ASK1 in the nucleus, cytoplasm, and in mitochondria. We propose that ASK2 regulates stress-induced caspase-3 and PARP cleavage in a dose-dependent manner by heteromeric complex formation with ASK1.
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Affiliation(s)
- Elisabeth Ortner
- Institute of Medical Virology, University of Zurich, Gloriastrasse 30, CH-8006 Zurich, Switzerland
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200
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von Bismarck P, Klemm K, Wistädt CFG, Winoto-Morbach S, Uhlig U, Schütze S, Uhlig S, Lachmann B, Krause MF. Surfactant “fortification” by topical inhibition of nuclear factor-κB activity in a newborn piglet lavage model*. Crit Care Med 2007; 35:2309-18. [DOI: 10.1097/01.ccm.0000281472.47067.45] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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