1-Methylthiodihydroceramide, a Novel Analog of Dihydroceramide, Stimulates Sphinganine Degradation Resulting in Decreased de Novo Sphingolipid Biosynthesis

Echten‐Deckert, Gerhild van; Giannis, Athanassios; Schwarz, Andreas; Futerman, Anthony H.; Sandhoff, Konrad

doi:10.1074/jbc.273.2.1184

Cited by 33 publications

(31 citation statements)

References 40 publications

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“…37,38 The data demonstrate that all ceramide analogues and inhibitors that increase intracellular cellular levels (ie, DMAPP, an inhibitor of ceramidase that increases cellular ceramide levels 39 or PPMP, an inhibitor of glucosylceramide synthase) decrease ceramide de novo synthesis (Figure 1). Importantly, NB-DNJ, a glucosylceramide synthase inhibitor shown not to increase ceramide levels, equally does not affect ceramide de novo synthesis (Figure 1) or SRE-mediated gene transcription (Figure 3).…”

Section: Discussionmentioning

confidence: 99%

Ceramide Synthesis Correlates with the Posttranscriptional Regulation of the Sterol-Regulatory Element-Binding Protein

Worgall

Juliano

Seo

et al. 2004

ATVB

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Objective-Sterol-regulatory element-binding proteins (SREBPs) regulate transcription of genes of lipid metabolism.Ceramide decreases transcriptionally active SREBP levels independently of intracellular cholesterol levels. Mechanisms of the ceramide-mediated decrease of SREBP levels were investigated. T he sterol-regulatory element-binding proteins (SREBPs) are important transcription factors of genes of lipid metabolism. In sterol depletion, precursor SREBP is translocated from the endoplasmic reticulum by vesicular trafficking to the Golgi apparatus, 1,2 where the transcriptionally active mature SREBP is generated. Mature SREBP binds to sterolregulatory elements (SRE), cis-acting elements in the promoters of genes of cholesterol and fatty acid synthesis. 3 Cholesterol and unsaturated fatty acids are known regulators of transcriptional and posttranscriptional processing of SREBP. We recently reported that unsaturated fatty acidsmediated decreases in SRE-mediated gene transcription are linked to cellular sphingolipid metabolism. 4 Ceramide, a metabolite of sphingomyelin hydrolysis, also regulates mature SREBP levels. Regulation occurs even in the presence of inhibitors of intracellular cholesterol trafficking, suggesting a cholesterol-independent effect. 4 Ceramide has multiple roles ranging from lipid second messenger to the induction of apoptosis, cell growth, and differentiation. 5,6 Cellular ceramide levels are generated either by de novo synthesis from serine and palmitoyl-CoA or through a recycling pathway of sphingolipid hydrolysis. Methods and Results-ExperimentsCeramide also has a role in intracellular protein trafficking, can inhibit coated vesicle formation and exocytosis in Chinese hamster ovary (CHO) cells, 7 and can modulate endocytosis in mammalian cells. 8 In yeast, ongoing ceramide synthesis is critical in the vesicular ER-to-Golgi transport of GPI-anchored proteins. 9 -11 We investigated the effect of ceramide synthesis on SREBP levels and SRE-mediated gene transcription. Because increased ceramide levels decrease mature SREBP protein levels and SRE-mediated gene transcription, 4 it was anticipated that inhibition of ceramide synthesis should increase mature SREBP levels and SRE-mediated gene transcription. Contrary to this hypothesis, inhibition of ceramide synthesis decreases SRE-mediated gene transcription. Increasing ceramide synthesis correlates with increased mature SREBP levels and SRE-mediated gene transcription. Consequently, the effect of ceramide on its own synthesis was investigated and shown to be inhibitory, providing an explanation that increased ceramide levels and decreased ceramide synthesis inhibit SRE-mediated gene transcription. PlasmidsThe pSyn-SRE luciferase reporter plasmid originates from the hamster HMG-CoA synthase promoter and contains three SRE elements (Ϫ326 to Ϫ225 bp) and has been described before. 14,15 The pWLNeo plasmid was obtained from Stratagene (La Jolla, Calif). Cell Culture and Stable TransfectionsCells were grown in F12-nutrient mixture medium contai...

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Section: Discussionmentioning

confidence: 99%

Ceramide Synthesis Correlates with the Posttranscriptional Regulation of the Sterol-Regulatory Element-Binding Protein

Worgall

Juliano

Seo

et al. 2004

ATVB

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“…Granule cells were cultured from cerebella of 6-dayold mice as described previously (van Echten-Deckert et al, 1998). In brief, cells were isolated by mild trypsinization [0.05% (w/v)] and dissociated by repeated passage through a constricted Pasteur pipette in a DNase solution [0.1% (w/v)].…”

Section: N-[1-mentioning

confidence: 99%

“…The idea that an inhibitor of dihydroceramide desaturation and hence of de novo ceramide formation might possibly be a useful cell protective agent, prompted us to investigate the effects of GT11 in primary cultured cerebellar neurons. In addition to being a validated model for studies concerning synthetic analogs that interfere with SL metabolism (van , 1998, these cells could also provide data concerning a potential pharmacological utility of GT11 as a neuroprotective drug. We report here that low concentrations (up to 1 M) of GT11 specifically and effectively inhibit dihydroceramide desaturase in primary cultured cerebellar neurons.…”

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Specificity of the Dihydroceramide Desaturase InhibitorN-[(1R,2S)-2-Hydroxy-1-hydroxymethyl-2-(2-tridecyl-1-cyclopropenyl)ethyl]octanamide (GT11) in Primary Cultured Cerebellar Neurons

Triola

Fabriás²,

Dragusin³

et al. 2004

Mol Pharmacol

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Dihydroceramide desaturase catalyzes the conversion of the innocuous precursor dihydroceramide into a highly bioactive product ceramide. We studied the effect of N-[(1R,2S)-2-hydroxy-1-hydroxymethyl-2-(2-tridecyl-1-cyclopropenyl)ethyl]octanamide (GT11), the first inhibitor of this enzyme, in primary cultured cerebellar neurons. Although desaturase was efficiently inhibited (IC 50 of 23 nM), the compound lost its specificity at higher concentrations. From 5 M upward, GT11 also decreased de novo sphingolipid biosynthesis. Studies with two differentially labeled radioactive analogs of GT11 support that the inhibitor itself and not a downstream metabolic product, interferes with sphingolipid biosynthesis. It is interesting that serine palmitoyltransferase activity decreased in the presence of high concentrations of GT11 in intact cells, but not when added directly into cell homogenates.

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“…Granule cells were cultured from cerebella of 6-day-old mice as described before (17). Briefly, cells were isolated by mild trypsinization (0.05%, w/v) and dissociated by repeated passage through a constricted Pasteur pipette in a DNase solution (0.1%, w/v).…”

Section: Cell Culturementioning

confidence: 99%

Metabolism of the unnatural anticancer lipid safingol, l-threo-dihydrosphingosine, in cultured cells

Dragusin

Gurgui²,

Schwarzmann

et al. 2003

Journal of Lipid Research

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We studied the metabolism of radioactively labeled safingol ( L -threo-dihydrosphingosine) in primary cultured neurons, B104 neuroblastoma cells, and Swiss 3T3 fibroblasts, and compared it to that of its natural stereoisomer D -erythro -dihydrosphingosine. Both sphingoid bases are used as biosynthetic precursors for complex sphingolipids, albeit to different rates. Whereas a considerable amount of the natural sphingoid base is also directed to the catabolic pathway (20-66%, cell type dependent), only a minor amount of the nonnatural safingol is subjected to catabolic cleavage, most of it being N -acylated to the respective stereochemical variant of dihydroceramide. Interestingly, N -acylation of safingol to L -threo -dihydroceramide is less sensitive to fumonisin B1 than the formation of the natural D -erythro -dihydroceramide. In addition, safingol-derived L -threo-dihydroceramide, unlike its physiologic counterpart, is not desaturated. Most of it either accumulates in the cells (up to 50%) or is used as a biosynthetic precursor of the respective dihydrosphingomyelin (up to 45%). About 5% is, however, glucosylated and channeled into the glycosphingolipid biosynthetic pathway. Our results demonstrate that, despite its nonnatural stereochemistry, safingol is recognized and metabolized preferentially by enzymes of the sphingolipid biosynthetic pathway. Furthermore, our data suggest that the cytotoxic potential of safingol is reduced rather than enhanced via its metabolic conversion. -Dragusin, M., C. Gurgui, G. Schwarzmann, J. Hoernschemeyer, and G. van Echten-Deckert. Metabolism of the unnatural anticancer lipid safingol, L -threo -dihydrosphingosine, in cultured cells.

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1-Methylthiodihydroceramide, a Novel Analog of Dihydroceramide, Stimulates Sphinganine Degradation Resulting in Decreased de Novo Sphingolipid Biosynthesis

Cited by 33 publications

References 40 publications

Ceramide Synthesis Correlates with the Posttranscriptional Regulation of the Sterol-Regulatory Element-Binding Protein

Ceramide Synthesis Correlates with the Posttranscriptional Regulation of the Sterol-Regulatory Element-Binding Protein

Specificity of the Dihydroceramide Desaturase InhibitorN-[(1R,2S)-2-Hydroxy-1-hydroxymethyl-2-(2-tridecyl-1-cyclopropenyl)ethyl]octanamide (GT11) in Primary Cultured Cerebellar Neurons

Metabolism of the unnatural anticancer lipid safingol, l-threo-dihydrosphingosine, in cultured cells

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